septin ring

GO:0005940 · Cytoskeleton · Filament · Proposed

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. [GO:0005940]

Part of: cell cortex (GO:0005938)

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
septin proteins	Protein	part of	Reviewed label only (reviewed name; no accession asserted)			ESSENTIAL	GTP-binding filament-forming proteins that oligomerize, polymerize, and organize into a cortical ring at fungal cytokinesis sites. `DOI:10.3389/fcell.2016.00123` Glomb and Gronemeyer 2016 review Saccharomyces cerevisiae Cdc3, Cdc10, Cdc11, Cdc12, and Shs1 as mitotic septins that assemble at the bud neck. `DOI:10.1534/genetics.107.073007` Iwase et al. 2007 studied Shs1/Sep7 with the Cdc3, Cdc10, Cdc11, and Cdc12 septins of the budding-yeast septin ring.

Taxonomic distribution

NCBITaxon:4751 Fungi — COMMON: Fungal septins organize into higher-order structures during morphology, septation, and virulence programs, with assembly context varying across budding, filamentous, and pathogenic fungi. [DOI:10.1099/mic.0.000359]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Budding-yeast model in which Cdc3/Cdc10/Cdc11/Cdc12/Shs1 septins form a ring at the mother-bud neck. [DOI:10.1534/genetics.107.073007]

Functions

cytokinesis-site scaffolding — The fungal septin ring marks the future division site and scaffolds cytokinesis factors at the mother-bud neck or fungal septation site.
- DOI:10.3389/fcell.2016.00123 Glomb and Gronemeyer 2016 review septin organization and cytokinesis functions at the budding-yeast bud neck.
- DOI:10.1016/j.mib.2014.04.004 Bridges and Gladfelter 2014 review fungal septins as scaffolds in division and polarity, including pathogenic-fungus models.

Mechanism graphs

Budding-yeast septin hetero-octamers polymerize into a cortical ring (ASSEMBLY)

In Saccharomyces cerevisiae, septin proteins assemble into hetero-octameric rods, the rods polymerize into septin filaments, and septin filaments organize at the bud-neck cortex to form the septin ring.

Subject	Predicate	Object	Evidence
septin proteins	oligomerize into	budding-yeast septin hetero-octamer	`DOI:10.1073/pnas.0803330105` Bertin et al. 2008 reconstituted Saccharomyces cerevisiae septin hetero-octamers and studied their supramolecular assembly.
budding-yeast septin hetero-octamer	polymerizes into	septin filaments	`DOI:10.1073/pnas.0803330105` Bertin et al. 2008 visualized purified budding-yeast septin hetero-octamers polymerizing into filaments. `DOI:10.1016/j.devcel.2011.02.004` McMurray et al. 2011 tested septin-filament formation in budding yeast.
septin filaments	assemble at	cell cortex	`GO:0005940` GO:0005940 defines the septin ring as a ring-shaped structure at the division plane. `DOI:10.3389/fcell.2016.00123` Glomb and Gronemeyer 2016 review septin-ring organization at the budding-yeast cortex.
septin ring	marks	cytokinesis site	`DOI:10.3389/fcell.2016.00123` Glomb and Gronemeyer 2016 review septin-ring organization and cytokinesis functions at the budding-yeast bud neck.

Discussions

CURATION_TODO (RESOLVED): Keep the septin ring distinct from the smaller septin hetero-oligomer complexes that polymerize into filaments. GO:0005940 denotes the higher-order cortical ring at the division plane. GO:0031105 denotes oligomeric septin protein complexes, so the complex belongs inside the assembly graph rather than as this record's identity.
CURATION_TODO (OPEN): Resolve exact source-neutral family groundings for fungal septin proteins if a family resource has a term matching the whole ring-forming cohort. The initial record leaves the septin-protein cohort reviewed-label only to avoid collapsing all fungal septin paralogs onto one guessed InterPro, Pfam, NCBIfam, or UniProtKB family accession.

Evidence

GO:0005940 Gene Ontology cellular-component term for the septin ring.
DOI:10.1534/genetics.107.073007 Iwase et al. 2007, 'Shs1 Plays Separable Roles in Septin Organization and Cytokinesis in Saccharomyces cerevisiae', Genetics.
DOI:10.1073/pnas.0803330105 Bertin et al. 2008, 'Saccharomyces cerevisiae septins: supramolecular organization of heterooligomers and the mechanism of filament assembly', Proceedings of the National Academy of Sciences USA.
DOI:10.1016/j.devcel.2011.02.004 McMurray et al. 2011, 'Septin Filament Formation Is Essential in Budding Yeast', Developmental Cell.
DOI:10.3389/fcell.2016.00123 Glomb and Gronemeyer 2016, 'Septin Organization and Functions in Budding Yeast', Frontiers in Cell and Developmental Biology.
DOI:10.1016/j.mib.2014.04.004 Bridges and Gladfelter 2014 review fungal septins as filament-forming scaffolds in cell division, polarity, and membrane-remodeling functions.
DOI:10.1099/mic.0.000359 Vargas-Muniz, Juvvadi, and Steinbach 2016 review fungal septin organization in higher-order structures across morphology, septation, and virulence contexts.

Curation history

2026-09-11T05:26:46Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-11T05:27:43Z codex · EXPANDED_RECORD — Added septin-cytoskeleton parentage, cell-cortex parthood, a septin protein component, Fungi taxonomy, a Saccharomyces cerevisiae canonical example, a cytokinesis-site scaffolding function, DOI/GO evidence, a septin oligomer-filament-ring assembly graph, and septin-complex boundary discussions.
2026-09-11T05:39:00Z codex · ADDRESSED_REVIEW — Resolved #420, #421, and #422 by narrowing the canonical example to the Iwase-supported bud-neck septin ring, scoping the hetero-octamer assembly graph to budding yeast, and typing the hetero-octamer and filament graph nodes as structures.
2026-09-21T19:44:46Z codex · ADDRESSED_REVIEW — Resolved #1262 by replacing unreadable Douglas et al. 2005 evidence with readable Vargas-Muniz et al. 2016 support for higher-order fungal septin organization and Bridges and Gladfelter 2014 plus existing Glomb and Gronemeyer 2016 support for fungal cytokinesis-site scaffolding.

Source: data/structures/cytoskeleton/septin_ring.yaml