septin cap

GO:0032159 · Cytoskeleton · Filament · Proposed

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. [GO:0032159]

Part of: GO:0005856 — cytoskeleton (no local record)

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	Septin GTPases that form the faint cap at the leading edge of filamentous fungal germ tubes and hyphae. `GO:0032159` GO:0032159 defines the septin cap as a structure formed of septins. `GO:0032156` — septin cytoskeleton GO:0032156 defines the broader septin cytoskeleton as cytoskeleton composed of septins and associated proteins.

Taxonomic distribution

NCBITaxon:5476 Candida albicans — VARIABLE: Candida albicans septin caps occur during the filamentous germ-tube and hyphal growth states rather than throughout all budding, pseudohyphal and hyphal morphologies. [DOI:10.1128/EC.4.9.1503-1512.2005]

Canonical examples

NCBITaxon:5476 Candida albicans — Candida model in which Warenda and Konopka reported GFP-labeled septins in emerging germ tubes and Douglas et al. reviewed the apical septin cap as a C. albicans germ-tube and hyphal septin structure. [DOI:10.1091/mbc.e02-01-0013]

Mechanism graphs

Septin-cap apical topology (ASSEMBLY)

Septin proteins form a faint cap at the leading edge of filamentous fungal germ tubes and hyphae.

Subject	Predicate	Object	Evidence
septin proteins	assemble into	septin cap	`GO:0032159` GO:0032159 defines the septin cap as a structure formed of septins.
septin cap	forms at	filamentous fungal growth tip	`GO:0032159` GO:0032159 localizes the septin cap to the leading edge of growth in germ tubes and hyphae.
septin cap	colocalizes with	ergosterol-rich plasma membrane region	`GO:0032159` GO:0032159 defines septin caps by colocalization with an ergosterol-rich plasma-membrane region.

Discussions

INTERPRETATION (RESOLVED): Keep the septin cap distinct from narrower germ-tube and hyphal septin caps and from septin rings or collars. GO:0032159 denotes the parent septin-cap structure at the leading edge of filamentous fungal growth. GO:0032171 and GO:0032164 are exact child terms for germ-tube and hyphal septin caps, whereas GO:0005940 and GO:0032173 model ring-shaped and collar-shaped septin structures.
CURATION_TODO (OPEN): Resolve exact source-neutral family groundings for septin-cap septin proteins. The first septin-cap record uses a reviewed-label-only septin protein cohort rather than guessing InterPro, Pfam, or NCBIfam accessions that may not exactly delimit all septins in this apical fungal cap.

Evidence

GO:0032159 Gene Ontology cellular-component term for the septin cap.
GO:0032156 — septin cytoskeleton Gene Ontology cellular-component parent term for the septin cytoskeleton.
GO:0005856 — cytoskeleton OLS reports a direct GO:0032159 part_of relation to the cytoskeleton.
DOI:10.1128/EC.4.9.1503-1512.2005 Douglas et al. 2005, 'Septin function in yeast model systems and pathogenic fungi', Eukaryotic Cell.
DOI:10.1091/mbc.e02-01-0013 Warenda and Konopka 2002, 'Septin function in Candida albicans morphogenesis', Molecular Biology of the Cell.

Curation history

2026-09-30T11:00:36Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-30T11:02:33Z codex · EXPANDED_RECORD — Added septin-cap parentage, a reviewed-label-only septin constituent, Candida albicans scope and canonical example evidence, GO-backed apical cap topology, and cap-boundary and component-grounding discussions.
2026-09-30T11:25:41Z codex · ADDRESSED_REVIEW — Resolved #1822 from PR #1821 by removing an indirect Martin and Konopka sterol-polarization DOI from the septin-cap colocalization edge and top-level evidence.

Source: data/structures/cytoskeleton/septin_cap.yaml