mating projection actin fusion focus

GO:1990819 · Cytoskeleton · Other · Proposed

A focus at the mating projection tip where the cell wall is degraded during cytogamy. Actin filaments form an aster-like structure from this location. [GO:1990819]

Synonyms: actin fusion focus

Part of: mating projection tip (GO:0043332); GO:0015629 — actin 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
actin filaments	Protein	part of	Reviewed label only (reviewed name; no accession asserted)			UNKNOWN	Filamentous actin that assembles into the aster-like focus at the mating projection tip fusion site. `GO:1990819` GO:1990819 defines the focus as a site from which actin filaments form an aster-like structure. `DOI:10.1083/jcb.201411124` Dudin et al. 2015 analyzed formin-nucleated actin aster formation at the fission-yeast fusion site.

Taxonomic distribution

NCBITaxon:4896 Schizosaccharomyces pombe — VARIABLE: Fission-yeast mating cells form a formin-nucleated actin fusion focus at the mating projection tip fusion site. [DOI:10.1083/jcb.201411124]

Canonical examples

NCBITaxon:4896 Schizosaccharomyces pombe — Model in which Fus1-nucleated actin filaments and type V myosins concentrate hydrolases at the mating-cell fusion focus. [DOI:10.1083/jcb.201411124]

Functions

focused mating-cell wall dissolution — The actin fusion focus concentrates cell-wall hydrolases at the mating projection fusion site so wall dissolution occurs locally during cytogamy.
- GO:1990819 GO:1990819 defines the actin fusion focus as a focus where the cell wall is degraded during cytogamy.
- DOI:10.1083/jcb.201411124 Dudin et al. 2015 connected the actin focus and type V myosins with local hydrolase concentration and cell-wall dissolution.

Mechanism graphs

Fus1-nucleated actin asters concentrate hydrolase delivery for wall dissolution (FUNCTION)

During Schizosaccharomyces pombe mating, Fus1 nucleates actin filaments at the projection tip and the resulting actin fusion focus works with type V myosins to concentrate hydrolases at the cell-fusion site.

Subject	Predicate	Object	Evidence
Fus1 formin	nucleates	actin filaments	`DOI:10.1083/jcb.201411124` Dudin et al. 2015 identified Fus1 as the formin that nucleates actin at the fission-yeast fusion site.
actin filaments	assemble into	mating projection actin fusion focus	`GO:1990819` GO:1990819 defines the focus as the mating-tip site from which actin filaments form an aster-like structure. `DOI:10.1083/jcb.201411124` Dudin et al. 2015 studied formation of the formin-nucleated actin aster during fission-yeast cell fusion.
type V myosins	concentrate	cell-wall hydrolases	`DOI:10.1083/jcb.201411124` Dudin et al. 2015 implicated type V myosins in concentrating hydrolases at the actin focus.
mating projection actin fusion focus	focalizes	cell wall dissolution	`DOI:10.1083/jcb.201411124` Dudin et al. 2015 linked the actin focus to localized cell-wall dissolution during fission-yeast cell fusion.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral groundings and component boundaries for Fus1 formin, type V myosins, and fusion-focus cell-wall hydrolases. This first actin-fusion-focus record models the actin-filament aster directly and records Fus1, type V myosins, and hydrolases in the graph without guessing family-level InterPro, Pfam, or UniProtKB groundings.

Evidence

GO:1990819 Gene Ontology cellular-component term for the mating projection actin fusion focus.
GO:0015629 — actin cytoskeleton Gene Ontology cellular-component term for the actin cytoskeleton.
GO:0043332 Gene Ontology cellular-component term for the mating projection tip.
DOI:10.1083/jcb.201411124 Dudin et al. 2015, 'A formin-nucleated actin aster concentrates cell wall hydrolases for cell fusion in fission yeast', Journal of Cell Biology.

Curation history

2026-09-28T15:04:37Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-28T15:05:50Z codex · EXPANDED_RECORD — Added GO-backed actin-fusion-focus synonymy, actin-cytoskeleton and mating-projection-tip parthood, an actin-filament constituent, a Schizosaccharomyces example, Dudin et al. DOI evidence, a nonmechanistic Fus1-actin-focus wall-dissolution graph, and a component-boundary TODO.
2026-09-28T15:06:21Z codex · FIXED_NOTE — Corrected the formin-nucleated actin aster graph evidence note.
2026-09-28T15:23:23Z codex · ADDRESSED_REVIEW — Resolved #1730 by moving GO:0015629 actin cytoskeleton from parent_structures into part_of.

Source: data/structures/cytoskeleton/mating_projection_actin_fusion_focus.yaml