mating projection septin band

GO:0032162 · Cytoskeleton · Filament · Proposed

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). [GO:0032162]

Part of: mating projection (GO:0005937); GO:0032156 — septin 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)			UNKNOWN	Septin GTPases that form the diffuse set of bars at the neck of the mating projection. `GO:0032162` GO:0032162 defines the mating projection septin band as composed of septin bars at the shmoo neck. `DOI:10.1083/jcb.143.3.719` Longtine et al. 1998 visualized septins in pheromone-treated Saccharomyces cells as a fuzzy band or bars parallel to the projection axis.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — VARIABLE: Budding-yeast cells localize septins to a diffuse shmoo-neck band during pheromone-induced morphogenesis. [DOI:10.1083/jcb.143.3.719]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Pheromone-treated budding-yeast model in which septins appear as a fuzzy band or parallel bars at the shmoo neck. [DOI:10.1083/jcb.143.3.719]

Functions

shmoo-neck scaffolding — The diffuse shmoo-neck septin band is positioned with a pheromone-induced chitin band and can organize septin-associated morphogenesis factors at the projection neck.
- DOI:10.1083/jcb.143.3.719 Longtine et al. 1998 compared shmoo-neck septin localization with the chitin band deposited at mating-projection bases.
- DOI:10.1128/EC.4.9.1503-1512.2005 Douglas et al. 2005 reviewed scaffold functions for septins at the Saccharomyces shmoo neck.

Mechanism graphs

Shmoo-neck septin band topology (FUNCTION)

The mating projection septin band is a diffuse septin bar assembly at the neck of the pheromone-induced mating projection.

Subject	Predicate	Object	Evidence
septin proteins	form	mating projection septin band	`GO:0032162` GO:0032162 defines the band as a diffuse series of septin bars. `DOI:10.1083/jcb.143.3.719` Longtine et al. 1998 visualized septin bars parallel to the shmoo projection axis.
mating projection septin band	is part of	mating projection	`GO:0032162` GO:0032162 places the septin band at the neck of a shmoo mating projection.

Discussions

INTERPRETATION (RESOLVED): Keep the diffuse mating-projection septin band distinct from the ring-shaped GO:0032175 mating projection septin ring. GO:0032162 denotes a diffuse ring composed of parallel septin bars at the shmoo neck, whereas GO:0032175 denotes a ring-shaped septin structure. Longtine et al. 1998 describe Saccharomyces pheromone-response septins as a fuzzy band or bars, so this record captures the band morphology and leaves the GO:0032175 record separate.
CURATION_TODO (OPEN): Resolve an exact source-neutral grounding for the grouped septin proteins component, if one exists. GO:0032162 supports septins as structural constituents of the shmoo-neck band, but septins are a multi-paralog family and this record deliberately avoids guessing one InterPro, Pfam, or NCBIfam accession for the complete fungal septin cohort.

Evidence

GO:0032162 Gene Ontology cellular-component term for the mating projection septin band.
GO:0032158 Gene Ontology places GO:0032162 mating projection septin band directly under GO:0032158 septin band by is_a.
GO:0032156 — septin cytoskeleton Gene Ontology places GO:0032158 septin band in a part_of relation to GO:0032156 septin cytoskeleton. Cytoskeleton parthood is inherited by the GO:0032162 mating-projection band subtype; this is not an is-a relationship.
GO:0005937 Gene Ontology cellular-component term for the mating projection.
DOI:10.1083/jcb.143.3.719 Longtine et al. 1998, 'Role of the yeast Gin4p protein kinase in septin assembly and the relationship between septin assembly and septin function', Journal of Cell Biology.
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

2026-09-28T17:13:23Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-28T17:15:29Z codex · EXPANDED_RECORD — Added septin-cytoskeleton parentage, mating-projection parthood, a label-only septin constituent, Saccharomyces distribution and canonical example evidence, a shmoo-neck scaffold function, DOI/GO evidence, a nonmechanistic shmoo-neck band topology graph, and a resolved ring-versus-band interpretation.
2026-09-28T17:42:25Z codex · EXPANDED_RECORD — Added an open CURATION_TODO discussion for the reviewed-label-only septin proteins component, addressing issue #1734.
2026-10-11T14:27:25Z codex · ADDRESS_SAVED_REVIEW — Addressed #2218: Corrected the is-a parent to GO:0032158 septin band and represented the containing GO:0032156 septin cytoskeleton with part_of, retaining mating-projection parthood and adding typed GO evidence.

Source: data/structures/cytoskeleton/mating_projection_septin_band.yaml