mastigoneme
A hair-like structure covering the flagella found in some algae (heterokonts and cryptophytes). It is approximately 15 nm in diameter, and usually consist of a tubular shaft that itself terminates in smaller hairs. It is composed of glycoproteins and, likely, carbohydrates. Mastigonemes may assist in locomotion by increasing the surface area of a flagellum. [GO:0097741]
Part of: cilium (GO:0005929)
Components
| Component | Type | Part of / acts on | Grounding | Genes | Stoichiometry | Essential | Role |
|---|---|---|---|---|---|---|---|
| MST1 hydroxyproline-rich mastigoneme glycoprotein | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | MST1 | Major extracellular glycoprotein forming the Chlamydomonas mastigoneme filament.
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| MST3 hydroxyproline-rich mastigoneme glycoprotein | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | MST3 | Hydroxyproline-rich glycoprotein that co-assembles with MST1 in the Chlamydomonas mastigoneme.
| ||
| PKD2 mastigoneme organizer | Protein | acts on | Reviewed label only (reviewed name; no accession asserted) | PKD2 | Ciliary membrane protein that organizes Chlamydomonas mastigonemes on the ciliary surface.
|
Taxonomic distribution
NCBITaxon:3055Chlamydomonas reinhardtii — COMMON: The green alga Chlamydomonas reinhardtii carries mastigonemes on its cilia that are built from MST1 and MST3 glycoproteins. [DOI:10.1016/j.cell.2024.03.005]
Canonical examples
NCBITaxon:3055Chlamydomonas reinhardtii — Model alga in which PKD2-dependent organization of mastigonemes on the ciliary surface has been characterized. [DOI:10.1083/jcb.202001122]
Functions
- context-dependent contribution to swimming — Chlamydomonas mastigoneme-associated swimming phenotypes depend on the tested mutant and assay. Liu et al. 2020 observed slower swimming in an mst1 mutant, whereas Amador et al. 2020 found no significant forward-swimming speed or propulsive-flow benefit from mastigonemes using a different mstg line. A general hydrodynamic contribution is therefore not established.
DOI:10.1083/jcb.202001122Liu et al. 2020 found that mst1 line LMJ.RY0402.052413 lacked mastigonemes and swam about 15% slower than their control. PKD2 organization and swimming phenotypes support a context-specific association, not a resolved universal hydrodynamic mechanism.DOI:10.1016/j.bpj.2020.05.003Amador et al. 2020 used mastigoneme-deficient mstg line LMJ.RY0402.136134 and compared it with cw15 and cc125. Mean swimming speed, normalized maximum speed, flagellar waveform and propulsive flows did not show significant enhancement by mastigonemes under these conditions. Increased turning in mstg was observed, so this is not evidence that all motility phenotypes are absent.
Mechanism graphs
MST1/MST3 glycoproteins assemble into ciliary mastigonemes (ASSEMBLY)
In Chlamydomonas, MST1 and MST3 glycoproteins make up the mastigoneme filament, and PKD2 organizes the extracellular mastigoneme polymers on cilia.
| Subject | Predicate | Object | Evidence |
|---|---|---|---|
| MST1 hydroxyproline-rich glycoprotein | polymerizes into | mastigoneme |
|
| MST3 hydroxyproline-rich glycoprotein | co-assembles into | mastigoneme |
|
| PKD2 mastigoneme organizer | organizes | mastigoneme |
|
Discussions
- CURATION_TODO (OPEN): Resolve exact MST1, MST3 and PKD2 family groundings before adding protein examples or broader mastigoneme homolog sets. This first record curates the Chlamydomonas mastigoneme components by experimentally used symbols but does not assert InterPro, Pfam, NCBIfam or UniProt accessions for their full source-neutral families.
- CURATION_TODO (OPEN): Add clade-level heterokont, cryptophyte or stramenopile taxonomic rows only after resolving current NCBI taxonomy IDs and direct review evidence for that breadth. GO's textual definition mentions heterokonts and cryptophytes, but this pass adds only a Chlamydomonas species row backed by component-level primary papers and avoids guessing broad NCBITaxon CURIEs.
- INTERPRETATION (OPEN): Resolve why mastigoneme-deficient Chlamydomonas lines show different swimming results across experiments before assigning a general hydrodynamic or sensory mechanism. Liu et al. 2020 reported slower swimming for mst1 LMJ.RY0402.052413, whereas Amador et al. 2020 found no forward-speed or flow enhancement in comparisons using mstg LMJ.RY0402.136134. These are distinct mutant lines and assay contexts. Dai et al. 2024 also notes the conflicting literature while reporting a modest mst3 swimming phenotype. Neither a universal propulsion benefit nor a demonstrated sensory mechanism follows from these results.
Evidence
GO:0097741Gene Ontology cellular-component term for mastigoneme.PMID:943397Chen and Haines 1976, The flagellar membrane of Ochromonas danica. Isolation and electrophoretic analysis of the flagellar membrane, axonemes, and mastigonemes, Journal of Biological Chemistry.DOI:10.1083/jcb.202001122Liu et al. 2020, Chlamydomonas PKD2 organizes mastigonemes, hair-like glycoprotein polymers on cilia, Journal of Cell Biology.DOI:10.1016/j.cell.2024.03.005Dai et al. 2024, Mastigoneme structure reveals insights into the O-linked glycosylation code of native hydroxyproline-rich helices, Cell.
Curation history
2026-09-13T10:19:00Zcodex · CREATED_RECORD — Scaffolded by scripts/new_record.py2026-09-13T10:19:58Zcodex · EXPANDED_RECORD — Added cilium parthood, MST1, MST3 and PKD2 components, Chlamydomonas reinhardtii scope, a Chlamydomonas canonical example, a ciliary-surface motility function, mastigoneme literature evidence, an MST1/MST3/PKD2 assembly graph, and curation TODOs for protein grounding and broader taxonomic scope.2026-09-13T10:26:24Zcodex · ADDRESS_REVIEW — Narrowed the Chlamydomonas canonical example to the PKD2-dependent mastigoneme organization claim supported by its 2020 JCB reference; tracked by GitHub issue #773.2026-10-11T04:06:42Zclaude · ADDRESS_SAVED_REVIEW — Addressed #2169: qualified the swimming function with distinct Liu and Amador mutant/assay results and added an OPEN interpretation of the conflict, preserving the supported assembly graph.