germ tube septin cap

GO:0032171 · Cytoskeleton · Filament · Proposed

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. [GO:0032171]

Part of: GO:0032179 — germ tube (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. `GO:0032171` GO:0032171 defines the germ tube septin cap as a structure formed of septins. `GO:0032159` GO:0032159 defines the broader septin cap as a structure formed of septins.

Mechanism graphs

Germ-tube septin-cap apical topology (ASSEMBLY)

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

Subject	Predicate	Object	Evidence
septin proteins	assemble into	germ tube septin cap	`GO:0032171` GO:0032171 defines the germ tube septin cap as a structure formed of septins.
germ tube septin cap	forms at	germ-tube growth tip	`GO:0032171` GO:0032171 localizes the germ tube septin cap to the leading edge of growth in germ tubes.
germ tube septin cap	colocalizes with	ergosterol-rich plasma membrane region	`GO:0032171` GO:0032171 defines germ tube septin caps by colocalization with an ergosterol-rich plasma-membrane region.
germ tube septin cap	is part of	germ tube	`GO:0032171` The GO:0032171 graph places the germ tube septin cap in a part_of relation to GO:0032179.

Discussions

INTERPRETATION (RESOLVED): Keep the germ tube septin cap distinct from the generic septin cap, the hyphal cap, and germ-tube septation-site rings. GO:0032171 denotes the apical septin cap at the leading edge of filamentous fungal germ tubes. GO:0032159 denotes the broader hyphal-or-germ-tube septin-cap class, GO:0032164 denotes the hyphal cap sibling, and GO:0032172 denotes a ring-shaped septin structure at future germ-tube septation sites.
CURATION_TODO (OPEN): Resolve exact source-neutral family groundings for germ-tube-cap septin proteins. The first germ tube 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 germ-tube cap.

Evidence

GO:0032171 Gene Ontology cellular-component term for the germ tube septin cap.
GO:0032159 Gene Ontology cellular-component parent term for the septin cap.
GO:0032179 — germ tube Gene Ontology cellular-component term for the germ tube.
DOI:10.1128/EC.4.9.1503-1512.2005 Douglas et al. 2005, 'Septin function in yeast model systems and pathogenic fungi', Eukaryotic Cell.

Curation history

2026-09-30T12:23:23Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-30T12:24:23Z codex · EXPANDED_RECORD — Added GO-backed septin-cap parentage and germ-tube parthood, a reviewed-label-only septin constituent, GO-backed germ-tube apical-cap topology, and cap-boundary and component-grounding discussions.
2026-09-30T12:25:04Z codex · FIXED_GRAPH_NODE — Added the GO:0032179 germ tube structure node referenced by the germ tube septin cap part_of graph edge.

Source: data/structures/cytoskeleton/germ_tube_septin_cap.yaml