cellular bud neck septin collar

GO:0032174 · Cytoskeleton · Filament · Proposed

A tubular structure with flared ends, shaped like an hourglass and composed of highly ordered arrays of septin filaments, that forms at the bud neck of a dividing cell. In S. cerevisiae, this structure is located at the bud neck throughout most of the cell cycle and the septins are fixed within the structure, not exchanging with soluble septins. This septin structure acts as a scaffold for other proteins that function at the bud neck. [GO:0032174]

Part of: cellular bud neck (GO:0005935)

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 hourglass-shaped, ordered filament collar at the Saccharomyces mother-bud neck. `GO:0032174` GO:0032174 defines the cellular bud neck septin collar as an hourglass-shaped array of septin filaments at the bud neck. `DOI:10.1016/j.tcb.2005.06.007` Versele and Thorner 2005 reviewed budding-yeast septin filament polymerization as required for septin-collar assembly.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: Budding-yeast cells reorganize the initial septin ring into an hourglass-shaped septin collar at the mother-bud neck after budding. [DOI:10.1091/mbc.E04-09-0764]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Budding-yeast model in which Bni4 and Kcc4 reporters were used to follow asymmetry of proteins associated with the septin ring and the mother-bud-neck septin collar. [DOI:10.1091/mbc.E04-09-0764]

Functions

bud-neck scaffold — The cellular bud neck septin collar acts as an hourglass-shaped septin scaffold that organizes proteins functioning at the Saccharomyces mother-bud neck.
- GO:0032174 GO:0032174 defines the collar as a Saccharomyces bud-neck septin structure that scaffolds other proteins functioning at the bud neck.
- DOI:10.1091/mbc.E04-09-0764 Kozubowski et al. 2005 tracked asymmetric Bni4 and Kcc4 localization relative to the septin ring and collar in Saccharomyces cerevisiae.

Mechanism graphs

Bud-neck septin collar topology (ASSEMBLY)

Septin proteins reorganize from an initial ring into an hourglass-shaped collar at the Saccharomyces mother-bud neck.

Subject	Predicate	Object	Evidence
septin proteins	assemble into	cellular bud neck septin collar	`GO:0032174` GO:0032174 defines the collar as an hourglass-shaped array of septin filaments.
cellular bud neck septin ring	rearranges into	cellular bud neck septin collar	`DOI:10.1091/mbc.E04-09-0764` Kozubowski et al. 2005 describe the Saccharomyces septin ring at the future budding site as rearranging into a collar at the mother-bud neck.
cellular bud neck septin collar	is part of	cellular bud neck	`GO:0032174` GO:0032174 places the septin collar at the bud neck of a dividing cell. `GO:0005935` GO:0005935 identifies the cellular bud neck.

Discussions

INTERPRETATION (RESOLVED): Keep the cellular bud neck septin collar distinct from the initial bud-neck septin ring and the cytokinetic split septin rings. GO:0000144 denotes the initial ring at the future bud site, GO:0032174 denotes the hourglass-shaped collar that forms at the bud neck for most of the cell cycle, and GO:0032177 denotes the two split rings formed from the collar at cytokinesis. This record models only the intervening collar state.
CURATION_TODO (OPEN): Resolve exact source-neutral family groundings for the bud-neck septin-collar septin proteins. The first localized collar record reuses the reviewed-label-only septin protein cohort from the broader septin-ring records rather than guessing InterPro, Pfam, or NCBIfam accessions that may not exactly delimit the complete fungal bud-neck collar.

Evidence

GO:0032174 Gene Ontology cellular-component term for the cellular bud neck septin collar.
GO:0032173 Gene Ontology cellular-component parent term for septin collar.
GO:0005935 Gene Ontology cellular-component term for the cellular bud neck.
DOI:10.1091/mbc.E04-09-0764 Kozubowski, Larson and Tatchell 2005, 'Role of the Septin Ring in the Asymmetric Localization of Proteins at the Mother-Bud Neck in Saccharomyces cerevisiae', Molecular Biology of the Cell.
DOI:10.1016/j.tcb.2005.06.007 Versele and Thorner 2005, 'Some assembly required: yeast septins provide the instruction manual', Trends in Cell Biology.

Curation history

2026-09-28T22:07:17Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-28T22:08:07Z codex · EXPANDED_RECORD — Added septin-collar parentage, bud-neck parthood, a label-only septin constituent, Saccharomyces distribution and canonical example evidence, a bud-neck scaffold function, a nonmechanistic ring-to-collar topology graph, and collar-boundary and grounding discussions.
2026-09-28T22:24:40Z codex · ADDRESSED_REVIEW — Resolved #1744 by broadening the bud-neck scaffold function beyond cytokinesis while preserving the ring/collar/split-ring boundary.

Source: data/structures/cytoskeleton/cellular_bud_neck_septin_collar.yaml