hyphal tip polarisome

GO:0031562 · Other · Multiprotein complex · Proposed

Protein complex that has a role in determining cell polarity, found at the tip of a growing fungal hypha. [GO:0031562]

Part of: GO:0001411 — hyphal tip (no local record)

Components

Component	Type	Part of / acts on	Grounding	Genes	Essential	Role
SPA-2 polarisome scaffold	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SPA-2	CONDITIONAL	Scaffold marker that partially overlaps the Spitzenkorper and extends into the apical dome of mature Neurospora hyphae. `DOI:10.1371/journal.pone.0030372` Lichius et al. 2012 compared BUD-6 and BNI-1 localization with SPA-2 as a bona fide Neurospora polarisome marker and integrated SPA-2 into the mature hyphal-tip architecture.
BUD-6 actin-associated polarity protein	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	BUD-6	CONDITIONAL	Actin-associated polarity protein that forms a subapical cloud around the Spitzenkorper in mature Neurospora hyphae. `DOI:10.1371/journal.pone.0030372` Lichius et al. 2012 localized BUD-6 to a dynamic subapical cloud that surrounds the Spitzenkorper during Neurospora mature hyphal-tip growth.
BNI-1 formin	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	BNI-1	CONDITIONAL	Formin that localizes in apical clusters and the Spitzenkorper core at mature Neurospora hyphal tips. `DOI:10.1371/journal.pone.0030372` Lichius et al. 2012 assayed BNI-1 and placed it in both the apical cap and Spitzenkorper core of the mature Neurospora hyphal tip.

NCBITaxon:5141 Neurospora crassa — COMMON: Neurospora mature hyphal tips carry SPA-2, BUD-6, and BNI-1 polarisome proteins in distinct apical-dome zones. [DOI:10.1371/journal.pone.0030372]

NCBITaxon:5141 Neurospora crassa — Filamentous fungal model in which SPA-2, BUD-6, and BNI-1 were compared by live-cell imaging during hyphal tip growth. [DOI:10.1371/journal.pone.0030372]

hyphal-tip polarity maintenance — The hyphal tip polarisome contributes to maintained polarized tip growth in Neurospora hyphae.
- GO:0031562 GO:0031562 defines the hyphal tip polarisome by its role in determining cell polarity at the tip of a growing fungal hypha.
- DOI:10.1371/journal.pone.0030372 Lichius et al. 2012 concluded that the Neurospora SPA-2, BUD-6, and BNI-1 arrangement in the mature apical dome is a filamentous tip-growth-apparatus architecture.

SPA-2, BUD-6, and BNI-1 occupy distinct zones in the Neurospora mature hyphal-tip apical dome.

Subject	Predicate	Object	Evidence
hyphal tip polarisome	is part of	hyphal tip	`GO:0031562` GO:0031562 defines the polarisome at a growing fungal hyphal tip. `GO:0001411` — hyphal tip GO:0001411 identifies the fungal hyphal tip.
SPA-2 polarisome scaffold	occupies	hyphal tip polarisome	`DOI:10.1371/journal.pone.0030372` Lichius et al. 2012 integrated SPA-2 as partially overlapping the Spitzenkorper and fanning into the Neurospora apical dome.
BUD-6 actin-associated polarity protein	occupies	hyphal tip polarisome	`DOI:10.1371/journal.pone.0030372` Lichius et al. 2012 observed BUD-6 as a subapical cloud that was excluded from the Spitzenkorper.
BNI-1 formin	occupies	hyphal tip polarisome	`DOI:10.1371/journal.pone.0030372` Lichius et al. 2012 localized BNI-1 to the Spitzenkorper core and to apical clusters in mature Neurospora hyphae.

CURATION_TODO (OPEN): Resolve exact source-neutral family groundings for Neurospora SPA-2, BUD-6, and BNI-1. The first hyphal-tip record keeps the Neurospora Spa2, Bud6, and Bni1 homologs label-only rather than guessing InterPro, Pfam, or NCBIfam groundings whose broader families may include paralogs outside this localized polarisome architecture.
INTERPRETATION (RESOLVED): Keep septal plugging, cell fusion, and cytokinesis roles outside the first hyphal-tip polarisome boundary. Lichius et al. 2012 observed SPA-2, BUD-6, and BNI-1 recruitment to septal plugs and identified BUD-6 and BNI-1 functions at cell-fusion sites, septa, and cytokinetic rings that are independent of the hyphal-tip polarisome, so those assemblies are excluded from the GO:0031562 component boundary until separate structure evidence is curated.

GO:0031562 Gene Ontology cellular-component term for the hyphal tip polarisome.
GO:0000133 Gene Ontology cellular-component term for polarisome.
GO:0001411 — hyphal tip Gene Ontology cellular-component term for the hyphal tip.
DOI:10.1371/journal.pone.0030372 Lichius et al. 2012, 'Comparative Live-Cell Imaging Analyses of SPA-2, BUD-6 and BNI-1 in Neurospora crassa Reveal Novel Features of the Filamentous Fungal Polarisome', PLoS ONE.

2026-09-28T20:33:17Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-28T20:35:11Z codex · EXPANDED_RECORD — Added polarisome parentage, hyphal-tip parthood, label-only SPA-2, BUD-6, and BNI-1 constituents, Neurospora distribution and canonical example evidence, a hyphal-tip polarity-maintenance function, a nonmechanistic mature-tip topology graph, and grounding and boundary discussions.
2026-09-28T20:35:57Z codex · REFINED_GRAPH — Focused the BNI-1 mature-tip topology edge on the hyphal tip polarisome record instead of using a separate Spitzenkorper node.
2026-09-28T20:57:09Z codex · ADDRESSED_REVIEW — Resolved #1740 by attaching the non-tip boundary discussion to SPA-2 and clarifying that SPA-2 septal-plug localization is outside the hyphal tip polarisome.