Cytoskeleton

The complete 13-protofilament A tubule of the axonemal doublet microtubule.

An amorphous cytoplasmic assembly of actin filaments and selected actin-binding proteins in growth-arrested yeast cells, distinct from cortical actin patches and actin cables.

An endocytic patch formed from branched actin filaments just beneath the plasma membrane that assembles, moves, and disassembles rapidly.

A cytokinetic cytoskeletal ring composed of actin filaments, myosin, and accessory proteins that assembles beneath the plasma membrane and constricts during cell division.

A plasmid-encoded bacterial actin-like cytoskeletal filament assembled from AlfA ATPases that supports segregation of pLS32-family plasmids in Bacillus subtilis.

The microtubule-inner-protein network inside the lumen of the A tubule of the axonemal doublet microtubule.

The microtubule-inner-protein network inside the lumen of the B tubule of the axonemal doublet microtubule.

A 9+2 axonemal subassembly of the central microtubule pair, its projections, its tubule-bridging structures, and caps on the microtubule plus ends.

A bridge network that connects the C1 and C2 singlet microtubules of the 9+2 axonemal central apparatus.

A pair of asymmetric C1 and C2 singlet microtubules at the center of the 9+2 axonemal central apparatus.

A projection structure that extends from the C1 or C2 singlet microtubule of the 9+2 axonemal central apparatus.

A cellular anatomical entity that is part of an axoneme consisting of a doublet microtubule.

A dynein complex found in eukaryotic cilia and flagella; the motor domain heads interact with adjacent microtubules to generate a sliding force which is converted to a bending motion.

A microtubule in the axoneme of a eukaryotic cilium or flagellum; an axoneme contains nine modified doublet microtubules, which may or may not surround a pair of single microtubules.

A structure that joins the B10 protofilament of the B tubule to the A1 protofilament of the A tubule within an axonemal microtubule doublet.

A structural network of microtubule inner proteins located inside the lumens of the A and B tubules of the axonemal microtubule doublet that helps stabilize the doublet microtubule.

A junctional axonemal doublet substructure that links the B-tubule B1 protofilament to A-tubule protofilaments A10 and A11.

A three-protofilament ribbon formed by A-tubule protofilaments A11, A12 and A13 plus associated microtubule inner proteins that separates the A- and B-tubule lumens within an axonemal doublet microtubule.

A protein complex in ciliary and flagellar axonemes that interconnects neighboring outer doublet microtubules.

A microtubule-based bundle with associated proteins that forms the core of a eukaryotic cilium or flagellum.

The incomplete 10-protofilament B tubule of the axonemal doublet microtubule.

A cytoskeletal filament assembled from beta-helical bactofilin proteins. In bacteria, these filaments provide scaffolds for species-specific cellular organization, including polar stalk biogenesis in Caulobacter vibrioides.

A protein network at the lumen-facing interface between the A- and B-tubules of a basal-body triplet microtubule, forming connections between the two tubules with region-specific composition.

A proteinaceous intertriplet linkage connecting the A-microtubule of one triplet to the C-microtubule of the neighboring triplet in the wall of a ciliary basal body.

A microtubule-associated subassembly in the proximal region of a ciliary basal body, identified in Paramecium tetraurelia as a protruding density between A-microtubule protofilaments A8 and A9, adjacent to but distinguishable from the A-C linker.

A proteinaceous junction network at the lumen-facing interface between the B- and C-tubules of a basal-body triplet microtubule, connecting the two tubules with region-dependent composition.

A hook-shaped proteinaceous linker at the external B-C interface of a basal-body microtubule triplet. In the distal half of isolated Chlamydomonas reinhardtii basal bodies, hook densities occupy the C1 position, extend across the outer surfaces of C2-C4, and recur along the triplet axis.

A crescent-shaped proteinaceous filament inside the lumen of a basal-body C-tubule, spanning from protofilament C3 to the C6-C7 junction and occurring in a longitudinally repeated array in the distal half of isolated Chlamydomonas reinhardtii basal bodies.

A proteinaceous hub-and-spoke assembly at the proximal region of a microbial ciliary basal body or pro-basal body. Its central hub bears nine radially arranged spokes that connect toward the surrounding microtubules; the hub and spokes extend longitudinally as a stacked scaffold.

A morphologically distinct subassembly within the lumen of a microbial basal-body cartwheel hub, observed as a central electron-dense unit separate from the surrounding hub rings and radial spokes. Such units can repeat along the cartwheel axis, with nonuniform occupancy.

A longitudinal subassembly at the periphery of a microbial ciliary basal-body or pro-basal-body cartwheel, linking the outer radial-spoke ends along the cartwheel axis. In characterized Chlamydomonas and Paramecium regions it is distinguishable from the pinhead and extends into the proximal cartwheel segment beyond the microtubule wall.

An apparently continuous filamentous subassembly extending longitudinally within the lumen of a microbial basal-body cartwheel hub. It is morphologically distinguishable from the surrounding hub rings and spokes and from discontinuous cartwheel inner-density units.

A proteinaceous meshwork lining the lumen-facing surface of the central basal-body wall and interconnecting neighboring triplet microtubules through multiple attachment sites.

A proteinaceous subassembly on the luminal face of the A-tubule in the proximal region of a microbial ciliary basal body or pro-basal body, forming the peripheral connection toward the cartwheel spokes. In Chlamydomonas reinhardtii it has a bent pinbody and two pinfeet attached to protofilament A3.

A linker in the proximal region of a microbial ciliary basal body that connects the pinhead to the A-C linker. In Paramecium tetraurelia reconstructions it extends to the ArmB region of the A-C linker.

An electron dense ring at the most posterior position of the apical complex, from which the subpellicular microtubules originate; formed during an invasive life cycle stage of an apicomplexan parasite.

A cytoskeletal structure in some kinetoplastid species linking the structures of the ciliary pocket collar and the flagellum attachment zone.

A bacterial cytoskeletal microtubule assembled from BtubA and BtubB tubulin homologs that form tube-like filaments in Prosthecobacter cells and in purified BtubA/B reactions.

The asymmetric C1 singlet microtubule of the axonemal central pair.

The asymmetric C2 singlet microtubule of the axonemal central pair.

A contractile ring, i.e. a cytoskeletal structure composed of actin filaments and myosin, that forms beneath the plasma membrane at the mother-bud neck in mitotic cells that divide by budding in preparation for completing cytokinesis. An example of this structure is found in Saccharomyces cerevisiae.

A tubular structure with flared ends, shaped like an hourglass and composed of highly ordered arrays of septin filaments, that forms at the bud neck of a dividing cell. In S. cerevisiae, this structure is located at the bud neck throughout most of the cell cycle and the septins are fixed within the structure, not exchanging with soluble septins. This septin structure acts as a scaffold for other proteins that function at the bud neck.

A ring-shaped structure that forms at the site of cytokinesis in the bud neck of a budding cell; composed of members of the conserved family of filament forming proteins called septins as well as septin-associated proteins. In S. cerevisiae, this structure forms at the time of bud emergence and the septins show a high rate of exchange.

Two separate septin rings that are formed from the septin collar at the time of cytokinesis in cells that divide by budding. These two rings are thought to delineate a special compartment in which factors involved in cytokinesis are concentrated.

One of three laminate structures that form the mitotic spindle pole body; the central plaque is embedded in the nuclear envelope.

One of three laminate structures that form the spindle pole body; the central plaque is embedded in the nuclear envelope.

An archaeal tubulin-like cytoskeletal filament assembled from CetZ proteins that forms dynamic envelope-associated structures and supports cell-shape remodeling such as rod development in Haloferax volcanii.

Arrays of septin filaments, or bars, found in a series of filamentous structures. Observed in the chlamydospore membrane during chlamydospore formation.

A membrane-tethered, short cylindrical array of microtubules and associated proteins found at the base of a eukaryotic cilium or flagellum that derives from a centriole, anchors the cilium and nucleates axonemal microtubule growth.

A rod-shaped protein complex containing Centrin4 protein that flanks the flagellum attachment zone (FAZ) filament and the quartet microtubules.

A constriction site at the junction of the plasma, flagellar and flagellar pocket membranes where the flagellum emerges from the cell body. Observed in some unicellular eukaryotic species such as Chlamydomonas, Giardia and Trypanosoma.

A cytoskeleton-like structure, originating from the basal body at the proximal end of a cilium, and extending proximally toward the cell nucleus. Rootlets are typically 80-100 nm in diameter and contain cross striae distributed at regular intervals of approximately 55-70 nm.

Any of a series of structures composed of septins and septin-associated proteins localized to the cleavage plane which are involved in cytokinesis.

A spiral cytoskeletal structure located at the apical end of the apical complex in some apicomplexan parasites. Fibers form a left-handed spiral, and are comprised of tubulin protofilaments organized in a ribbon-like structure that differs from the conventional tubular structure characteristic of microtubules.

A bacterial intermediate filament-like cytoskeletal filament assembled from crescentin that localizes along the inner curvature of Caulobacter vibrioides cells and helps maintain their curved cell shape.

A peripheral centrin-positive cytoskeletal network observed in cryptophyte cells by ultrastructure expansion microscopy. It forms a regular hexagonal mesh in Rhinomonas nottbeckii and shows variable network patterns among Rhodomonas isolates. The assembly is distinct from basal-body-associated centrin structures and from the periplast itself.

A filamentous, membrane-less subcellular structure composed primarily of polymerized metabolic enzymes, most notably cytidine triphosphate synthase (CTPS). Cytoophidia are evolutionarily conserved structures found across archaea, bacteria, and eukaryotes.

Any microtubule in the cytoplasm of a cell.

A largely unbranched, centrin-containing extension of the infraciliary lattice associated with the cytostome-cytopharynx region, characterized in Paramecium. It is a named fibrillar substructure, not the entire lattice or the adjacent cytopharyngeal microtubular ribbons.

Inward projections of the cytoskeletal structures of the oral apparatus, which form a fiber that extends past the cytostome into the cytoplasm.

A centrin-containing fibrous bridge connecting the distal regions of paired flagellar basal bodies in green algae. It is distinct from proximal connecting fibers and nucleus-directed rootlets; cross-striation differs between the documented examples.

A filamentous cortical structure formed, in S. pombe, by the eisosome component Pil1.

A system of calmyonemin-containing contractile filament bundles associated with the bases of retractile apical ciliature in entodiniomorphid ciliates, characterized in Eudiplodinium maggii and Entodinium bursa. This record denotes the subkinetal bundles, not all other calmyonemin-positive arrays or the cilia themselves.

A microtubule organizing center formed by a band of gamma-tubulin that is recruited to a circumferential band of F-actin at the midpoint of a cell and which nucleates microtubules from the cell division site at the end of mitosis.

A network of cytoskeletal and membranous connections responsible for the lateral attachment of the cilium to the cell body in some trypanosomatid species.

A Giardia trophozoite cytoskeletal structure composed of short microtubule arrays that emanate from the caudal flagellar axonemes, anchor to dense rods running parallel to the posterior-lateral flagella, and after posterior-lateral flagellar emergence anchor to the epiplasm beneath the contractile tail membrane.

A faint structure formed of septins found at the leading edge of growth in germ tubes of fungal cells growing filamentously. This cap of septins colocalizes with a region of the plasma membrane that is rich in ergosterol.

A tight ring-shaped structure that forms in the division plane within the germ tube of filamentous fungi at sites where a septum will form; composed of septins as well as septin-associated proteins.

A protein complex involved in septin ring formation during mitosis. In Saccharomyces cerevisiae it consists of BNI5, CDC3, CDC10, CDC11, CDC12, GIN4, NAP1 and SHS1. At least 2 GIN4 molecules are involved.

Structure adjacent to the plaques of the mitotic spindle pole body.

Structure adjacent to the plaques of the spindle pole body.

An array of astral microtubules that emanates from the spindle pole body during meiosis and facilitates horsetail nuclear movement.

A septin collar in pathogenic fungi involved in the constriction of hyphae at the plant plasmodesma enabling penetration of an adjacent cell.

A septin band, i.e. a diffuse ring composed of a series of septin bars running parallel to the long axis of the cell, located at the junction between the mother cell and the germ tube (hypha) of a fungal cell growing filamentously.

A faint structure formed of septins found at the leading edge of growth in hyphae of fungal cells growing filamentously. This cap of septins colocalizes with a region of the plasma membrane that is rich in ergosterol.

A tight ring-shaped structure that forms in the division plane within hyphae of filamentous fungi at sites where a septum will form; composed of septins as well as septin-associated proteins.

A basal-body-associated centrin assembly described in Paramecium tetraurelia as a functional complex of ICL1e-subfamily proteins. It appears as a discrete ICL1e-positive dot and persists in cells lacking the extended infraciliary lattice; it is distinct from the whole lattice and from the complete infraciliary-lattice organizing-centre remnant.

A subcortical, calcium-responsive contractile network of centrin-containing filaments in Paramecium, assembled with Sfi1-like centrin-binding proteins. The mesh extends beneath the cell surface and is distinct from the basal-body-associated organizing centres and ICL1e complex that can persist when the extended lattice is lost.

An axonemal dynein complex that forms an inner dynein arm on ciliary and flagellar outer doublet microtubules.

One of three laminate structures that form the mitotic spindle pole body; the inner plaque is in the nucleus.

One of three laminate structures that form the spindle pole body; the inner plaque is in the nucleus.

The layer of the mitotic spindle pole body between the central plaque and the outer plaque.

The layer of the spindle pole body between the central plaque and the outer plaque.

A microtubule organizing center found in interphase cells, which organize a longitudinal array of three to five MT bundles from the nuclear envelope during interphase. Each MT bundle is composed of two to seven MTs arranged in an antiparallel configuration, with the dynamic MT plus ends extending toward the cell tips and stable minus ends near the nucleus.

A SIN signaling complex associated with the old spindle pole body during interphase in an inhibitory configuration. In Schizosaccharomyces pombe, the Byr4-Cdc16 GAP inhibits the Spg1 GTPase. Dma1-dependent ubiquitination of the Sid4 scaffold antagonizes Plo1 recruitment in G2 and during a mitotic checkpoint arrest.

A microtubule located such that it threads through the conoid and projects through the polar ring.

An actin-like bacterial cytoskeletal filament assembled from MamK proteins that runs alongside magnetosomes in magnetotactic bacteria and helps organize the organelles into chains.

A focus at the mating projection tip where the cell wall is degraded during cytogamy. Actin filaments form an aster-like structure from this location.

A septin band, i.e. a diffuse ring composed of a series of septin bars running parallel to the long axis of the cell, located at the neck of a shmoo (mating projection).

A septin ring, i.e. a ring-shaped structure composed of septins and septin-associated proteins, located at the neck of a shmoo (mating projection). The septin ring in the neck of a shmoo may act as a barrier to localize mating factors in the shmoo tip.

A ring-shaped structure that forms at the medial cortex of a symmetrically dividing cell at the onset of cytokinesis; composed of members of the conserved family of filament forming proteins called septins as well as septin-associated proteins.

A non-membrane bound, semi-organized microtubule array of unknown function found in Giardia species (trophozoite stage). It is located on the dorsal side of the trophozoite, slightly posterior to the ventral disc.

A cytoskeletal structure composed of actin filaments, myosin, and myosin-associated proteins that forms beneath the plasma membrane of many cells, including animal cells and yeast cells, in a plane perpendicular to the axis of the meiotic spindle, i.e. the cell division plane. Ring contraction is associated with centripetal growth of the membrane that divides the cytoplasm of the two future daughter cells. In animal cells, the meiotic contractile ring is located inside the plasma membrane at the location of the cleavage furrow. In fungal cells, the meiotic contractile ring forms beneath the plasma membrane of the prospore envelope in preparation for completing cytokinesis.

A sporulation-specific cytoplasmic plaque that forms on meiosis II spindle pole bodies in budding yeast after outer-plaque remodeling and nucleates prospore membrane assembly.

A heterooligomeric septin complex that acts during meiotic cell division.

The microtubule organizing center that forms as part of the meiotic cell cycle; functionally homologous to the animal cell centrosome.

Any of the long, generally straight, hollow tubes of internal diameter 12-15 nm and external diameter 24 nm found in a wide variety of eukaryotic cells; each consists (usually) of 13 protofilaments of polymeric tubulin, staggered in such a manner that the tubulin monomers are arranged in a helical pattern on the microtubular surface, and with the alpha/beta axes of the tubulin subunits parallel to the long axis of the tubule; exist in equilibrium with pool of tubulin monomers and can be rapidly assembled or disassembled in response to physiological stimuli; concerned with force generation, e.g. in the spindle.

A cytoskeletal structure composed of actin filaments, myosin, and myosin-associated proteins that forms beneath the plasma membrane of many cells, including animal cells and yeast cells, in a plane perpendicular to the axis of the mitotic spindle, i.e. the cell division plane. Ring contraction is associated with centripetal growth of the membrane that divides the cytoplasm of the two future daughter cells. In animal cells, the mitotic contractile ring is located inside the plasma membrane at the location of the cleavage furrow. In Saccharomyces cerevisiae, Myo1 localizes to a ring at the future bud site before bud emergence; actin joins this ring at the mother-bud neck near the end of anaphase to form the cytokinetic actomyosin ring.

A heterooligomeric septin complex that acts during mitotic cell division.

A spindle that forms as part of mitosis. Mitotic and meiotic spindles contain distinctive complements of proteins associated with microtubules.

The microtubule organizing center that forms as part of the mitotic cell cycle; functionally homologous to the animal cell centrosome.

The actin-like cytoskeletal filament of rod-shaped bacteria. MreB polymerises into short membrane-associated filaments that circle the cell at an angle to its long axis and move processively around it, carrying the elongasome — the peptidoglycan synthases that widen the sidewall — so that new wall material is inserted where the filaments travel. It is a homologue of eukaryotic actin by fold, not by sequence identity.

The spindle pole body that is formed by spindle pole body duplication, and to which proteins involved in mitotic exit signaling (for example, the septation initiation network in fission yeast) localize.

A SIN signaling complex associated with the new mitotic spindle pole body during anaphase and characterized by the presence activated (GTP bound) GTPase (Spg1 in fission yeast) to activate SIN signaling.

Any microtubule in the nucleus of a cell.

A centrin-containing fibrous root system that links flagellar basal bodies to the nuclear surface. It is a specialized nucleus-associated rootlet system, not the entire basal apparatus or the fibers connecting basal bodies to one another.

The spindle pole body that existed before the most recent spindle pole body duplication. In unperturbed Schizosaccharomyces pombe mitosis, septation initiation network activity becomes restricted to the new pole in late anaphase B, after activity at both poles earlier in mitosis.

An axonemal dynein complex that forms the outer dynein arm on ciliary and flagellar outer doublet microtubules and contains dynein heavy, intermediate and light chains.

One of three laminate structures that form the mitotic spindle pole body; the outer plaque is in the cytoplasm.

One of three laminate structures that form the spindle pole body; the outer plaque is in the cytoplasm.

A plasmid-encoded bacterial actin-like cytoskeletal filament assembled from ParM that is captured and stabilized by ParR-parC plasmid-centromere complexes to support active segregation of low-copy-number plasmids such as Escherichia coli R1.

An interconnected contractile fiber system in the cell body of peritrich ciliates, comprising longitudinal and peristomial fibers. In Vorticella, body myonemes converge aborally into the distinct stalk spasmoneme. This record denotes the body network, not the stalk organelle, ciliary apparatus or an individual protein.

A phage-encoded tubulin-like cytoskeletal spindle assembled from PhuZ polymers that positions the jumbo-phage nucleus in infected bacterial cells.

An electron dense ring at the most anterior position of the apical complex, from which the conoid fibers originate; formed during an invasive life cycle stage of an apicomplexan parasite.

A cytoskeletal part that consists of an array of microtubules and associated molecules that forms at the end of anaphase, and in which microtubules are nucleated from an equatorial microtubule organizing center.

A contractile ring composed of actin filaments and myosin that forms beneath the plasma membrane of the prospore envelope in meiotic cells in preparation for completing cytokinesis.

Arrays of septin filaments, or bars, found in a series of filamentous structures; observed in the prospore membrane during spore formation.

A tight ring-shaped structure that forms in the division plane at the site of cytokinesis in a prospore; composed of septins as well as septin-associated proteins.

A tight ring-shaped structure that forms in the division plane at the junction between the mother cell and a pseudohyphal projection; composed of septins as well as septin-associated proteins.

A stable antiparallel cytoplasmic microtubule bundle assembled during nutrient-exhaustion-induced quiescence in fission yeast, characterized in Schizosaccharomyces pombe. It contains closely packed microtubules, is usually associated with the spindle pole body, and is distinct from the nuclear microtubule array of quiescent budding yeast.

A stable monopolar bundle of parallel nuclear microtubules formed during glucose-exhaustion-induced quiescence, characterized in Saccharomyces cerevisiae. The bundle extends from the nuclear face of the spindle pole body and reorganizes kinetochore and centromere distribution; it is distinct from the antiparallel cytoplasmic quiescent-cell bundle of fission yeast.

A transient, Hrs1/Mcp6-dependent, gamma-tubulin-enriched amorphous microtubule-organizing assembly at the cytoplasmic side of the spindle pole body during Schizosaccharomyces pombe meiotic prophase, distinct from the spindle pole body core, that organizes the radial microtubule array used in horsetail nuclear movement.

A ciliary and flagellar axonemal protein complex with a stalk attached to each outer-doublet A-tubule and a head that projects toward the central-pair microtubule sheath.

Protein complex forming portion of the radial spoke that is orthogonal to the elongated stalk and which projects towards the central pair of microtubules within the ciliary or flagellum axoneme.

The radial spoke neck is a complex that connects the spoke stalk to the head.

Protein complex forming the elongated portion of the radial spoke between the base which binds to the A-tubule of each microtubule outer doublet and the neck which connects to the spoke head within the ciliary or flagellum axoneme.

A diffuse ring composed of a series of septin bars that run parallel to the long axis of the cell. This type of septin structure has been observed in a number of locations associated with polarized growth and/or deposition of new membrane, but not with cytokinesis, such as at the shmoo (mating projection) neck, at the junction between the mother cell and the germ tube (hypha) of a fungal cell growing filamentously.

A faint structure formed of septins found at the leading edge of growth in germ tubes and hyphae in fungal cells growing filamentously. This cap of septins colocalizes with a region of the plasma membrane that is rich in ergosterol.

A tubular, hourglass-shaped structure composed of highly ordered arrays of septin filaments; in budding yeast cells, the septin collar forms from the initial septin ring by expanding into the daughter cell.

A protein complex containing septins. Typically, these complexes contain multiple septins and are oligomeric.

Arrays of septin filaments, or bars, found in a series of filamentous structures. Such structures have been observed in the prospore membrane during spore formation in S. cerevisiae and in the chlamydospore membrane during chlamydospore formation in C. albicans.

A tight ring-shaped septin-based cytoskeletal structure that forms at the cell cortex in the division plane, including the bud-neck septin ring of budding yeast and related fungal septin rings at septation sites.

A protein complex associated with the mitotic spindle pole body during interphase and mitosis and comprises of the proteins of the septation initiation signaling network (SIN) of fission yeast or mitotic exit network (MEN) of budding yeast, organized by two scaffold/adaptor proteins.

A protein complex that acts as a two-component GTPase-activating protein for the Tem1/Spg1 GTPase, thus regulating a signal transduction cascade (the mitotic exit network, MEN, in budding yeast; the septation initiation network, SIN, in fission yeast), which is required for mitotic exit and cytokinesis. The complex keeps the GTPase inactive until the spindle is properly oriented, thus inhibiting MEN/SIN activation.

A striated, wedge-shaped fibrous linker connecting a flagellar basal body to a five-microtubule s-type root in Spermatozopsis similis. Its BAp95-containing assembly is distinct from the root microtubules, SF-assemblin fibers, centrin fibers and proximal interbasal plates.

Any microtubule that is part of a mitotic or meiotic spindle; anchored at one spindle pole.

The microtubule-organizing center in fungi, functionally homologous to the animal centrosome.

A transient cytoplasmic plaque intermediate formed after spindle pole body satellite expansion during daughter spindle pole body assembly in budding yeast.

A transient cytoplasmic precursor of the daughter spindle pole body that forms at the distal tip of the half bridge during spindle pole body duplication in budding yeast.

A mesh-like cortical myoneme characterized in Spirostomum, containing intersecting centrin/spasmin-rich fibrillar bundles and giant Sfi1-like scaffold proteins. The extended network shortens during calcium-triggered cell contraction and is distinct from adjacent microtubule bundles and from an isolated scaffold-centrin protein complex.

A pair of rings that flank the site of cell division, formed by splitting of the septin ring (or collar) prior to cytokinesis; this double ring structure is thought to trap proteins needed for cytokinesis or the formation of the new membrane or cell wall between the two septin rings. Split septin rings are known to occur in budding yeast cells and probably occur in other cell types as well.

An intracellular contractile fibrillar organelle within the stalk of contractile-stalk peritrich ciliates. A spasmin-rich fibrillar mass is interspersed with membrane-bounded tubules. Shortening deforms the surrounding stalk; the organelle is distinct from the extracellular sheath and from the continuous body myoneme network.

A longitudinal cortical bundle of overlapping microtubule ribbons in Stentor, characterized ultrastructurally in S. coeruleus. Ribbons originate beside successive basal-body pairs and overlap alongside a ciliary row; the bundle is distinct from the deeper contractile myonemes.

The cortical system of longitudinal contractile filament bundles, historically termed M bands, characterized in Stentor coeruleus. Its prominent posterior myonemes are distinct from the adjacent microtubular Km fibers; this record does not denote every centrin-containing cortical assembly.

An irregular cortical microtubule meshwork characterized in Stentor pyriformis, with gaps occupied by algal endosymbionts in perialgal vacuoles. The named basket system denotes host cytoskeletal architecture, not regular cages, the symbionts themselves, their vacuole membranes, or the longitudinal Km-fiber bundles.

A singlet microtubule that lies underneath the inner membrane pellicle complex and emanates from the basal ring of the conoid.

A protein complex that contains the transforming acidic coiled coil (TACC) protein and the TOG protein (Mia1p/Alp7p and Alp14, respectively, in fission yeast), and is involved in microtubule array remodeling as cells progress through the cell cycle. The TACC/TOG complex is conserved in eukaryotes, associates with microtubules, and shuttles between the nucleus and the cytoplasm during interphase.

A telomere-associated microtubule organizing assembly formed at the nuclear envelope during meiotic entry in Schizosaccharomyces pombe. It recruits a gamma-tubulin nucleation complex to SUN/KASH-linked telomeres and generates cytoplasmic microtubules that support their clustering at the spindle pole body; it is distinct from the spindle pole body and the completed telomere bouquet.

A centrin-containing system of luminal fibers forming a nine-pointed stellate array attached to the outer microtubule doublets of the Chlamydomonas ciliary transition zone. It is distinct from the peripheral Y-links and from the central cylinder around which the fibers extend.

A three-part cytoskeletal structure in kinetoplastid species linking mitochondrial DNA organised in a kinetoplast through the mitochondrial membranes to the basal body.

A compact spool-like tubulin-positive cytoskeletal structure observed in kareniacean dinoflagellates. In Takayama helix, ultrastructure expansion microscopy resolves perinuclear and posterior spools that appear continuous with microtubules. The name denotes the assembled structure, not a tubulin protein or the entire cortical microtubule array.

A plasmid-encoded bacterial tubulin-like cytoskeletal filament assembled from TubZ GTPase subunits that supports pBtoxis plasmid partitioning in Bacillus thuringiensis.

A specialized organelle in Giardia trophozoites that supports attachment to host intestinal epithelium. Its spiral microtubule array bears dorsal microribbons linked by crossbridges, and a lateral crest surrounds the disc edge.

A fibrous structure that horizontally links adjacent dorsal microribbons in the ventral disc of Giardia species trophozoites.

Trilaminar structure extending perpendicularly into the cytoplasm along the length of ventral disc microtubules in Giardia species (trophozoite stage). Constituents of dorsal microribbons (also called dorsal ribbons or microribbons) include alpha-coiled-helix proteins approximately 29 to 38 kDa in size. These proteins line the edges of the microribbons but are not found in microtubules. Tubulins are not found in microribbons.

A fibrillar repetitive structure that surrounds the edge of the ventral disc in Giardia species trophozoites.

A part of the ventral disc of Giardia species (trophozoite stage) consisting of a spiral array of microtubules linked to the ventral membrane. These microtubules form the base of the ventral disc dorsal microribbons that extend nearly perpendicular from the membrane.

A region of the ventral disc of Giardia species (trophozoite stage) where two portions of the same array of microtubules overlap (the microtubule array makes a complete circle and overlaps on itself).

A partial spiral microtubule array associated with the Giardia trophozoite ventral disc and distinct from its main microtubule array. Schwartz et al. 2012 reconstructed a short right-handed fragment lying ventral to the main array.