COMA complex

GO:0000817 · Other · Multiprotein complex · Proposed

A kinetochore multiprotein complex that bridges the subunits that are in contact with centromeric DNA and the subunits bound to microtubules during kinetochore assembly. In yeast, consists of Ctf19p, Okp1p, Mcm21p, and Ame1p. [GO:0000817]

Part of: kinetochore (GO:0000776); nuclear chromosome (GO:0000228)

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Genes	Essential	Role
Ctf19 subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	CTF19	UNKNOWN	Named COMA constituent in the budding-yeast Ctf19p-Okp1p-Mcm21p-Ame1p kinetochore complex. `GO:0000817` GO:0000817 defines the yeast COMA complex as consisting of Ctf19p, Okp1p, Mcm21p and Ame1p. `DOI:10.1101/gad.1144403` De Wulf, McAinsh and Sorger 2003 placed Ctf19p in the budding-yeast COMA kinetochore subcomplex.
Okp1 subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	OKP1	UNKNOWN	Named COMA constituent in the budding-yeast Ctf19p-Okp1p-Mcm21p-Ame1p kinetochore complex. `GO:0000817` GO:0000817 defines the yeast COMA complex as consisting of Ctf19p, Okp1p, Mcm21p and Ame1p. `DOI:10.1101/gad.1144403` De Wulf, McAinsh and Sorger 2003 placed Okp1p in the budding-yeast COMA kinetochore subcomplex.
Mcm21 subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	MCM21	UNKNOWN	Named COMA constituent in the budding-yeast Ctf19p-Okp1p-Mcm21p-Ame1p kinetochore complex. `GO:0000817` GO:0000817 defines the yeast COMA complex as consisting of Ctf19p, Okp1p, Mcm21p and Ame1p. `DOI:10.1101/gad.1144403` De Wulf, McAinsh and Sorger 2003 placed Mcm21p in the budding-yeast COMA kinetochore subcomplex.
Ame1 subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	AME1	UNKNOWN	Named COMA constituent in the budding-yeast Ctf19p-Okp1p-Mcm21p-Ame1p kinetochore complex. `GO:0000817` GO:0000817 defines the yeast COMA complex as consisting of Ctf19p, Okp1p, Mcm21p and Ame1p. `DOI:10.1101/gad.1144403` De Wulf, McAinsh and Sorger 2003 placed Ame1p in the budding-yeast COMA kinetochore subcomplex.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: Budding yeast uses the four-protein Ctf19p-Okp1p-Mcm21p-Ame1p COMA complex as an inner kinetochore bridge. [DOI:10.1101/gad.1144403]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Reference yeast system in which COMA was placed between centromeric DNA-proximal and microtubule-bound kinetochore subcomplexes. [DOI:10.1101/gad.1144403]

Functions

inner-to-outer kinetochore bridging — COMA links centromeric DNA-proximal kinetochore subunits to microtubule-bound modules during kinetochore assembly.
- GO:0000817 GO:0000817 defines COMA by the bridge it forms between centromeric-DNA-proximal and microtubule-bound kinetochore subunits.
- DOI:10.1101/gad.1144403 De Wulf, McAinsh and Sorger 2003 analyzed COMA within a hierarchical budding-yeast kinetochore assembly pathway.

Mechanism graphs

COMA bridges centromere-proximal and microtubule-bound kinetochore layers (ASSEMBLY)

In budding yeast, the Ctf19p-Okp1p-Mcm21p-Ame1p COMA complex links centromeric DNA-proximal kinetochore subunits to microtubule-bound modules during kinetochore assembly.

Subject	Predicate	Object	Evidence
COMA complex	is part of	kinetochore	`GO:0000817` GO asserts GO:0000817 COMA complex part_of GO:0000776 kinetochore.
COMA complex	bridges to DNA-proximal side	centromeric DNA-proximal kinetochore subunits	`GO:0000817` GO:0000817 defines COMA by its bridge from centromeric DNA-proximal to microtubule-bound kinetochore subunits. `DOI:10.1101/gad.1144403` De Wulf, McAinsh and Sorger 2003 placed COMA between DNA-proximal and microtubule-bound budding-yeast kinetochore subcomplexes.
COMA complex	bridges to microtubule-bound side	microtubule-bound kinetochore subunits	`GO:0000817` GO:0000817 defines COMA by its bridge from centromeric DNA-proximal to microtubule-bound kinetochore subunits. `DOI:10.1101/gad.1144403` De Wulf, McAinsh and Sorger 2003 placed COMA between DNA-proximal and microtubule-bound budding-yeast kinetochore subcomplexes.

Discussions

CURATION_TODO (OPEN): Resolve the boundary between the yeast four-subunit COMA complex and the broader eukaryotic Ctf19/CCAN inner kinetochore network. This first COMA record stays at the four subunits named in GO:0000817 and avoids flattening additional Ctf19/CCAN factors into a single universally present component list.
CURATION_TODO (OPEN): Verify whether the GO:0000817 exact synonym Ctf19p-Okp1p-Mcm1p-Ame1p complex should be corrected to Mcm21p or curated as a historical spelling. The local GO metadata lists Ctf19p-Okp1p-Mcm1p-Ame1p complex as an exact synonym, while the GO definition and yeast subunit model name Mcm21p. This record omits that synonym until the spelling mismatch can be reviewed.

Evidence

GO:0000817 Gene Ontology cellular-component term for the COMA complex.
GO:0140513 Gene Ontology cellular-component parent term for nuclear protein-containing complexes.
GO:0000776 Gene Ontology cellular-component term for kinetochore.
GO:0000228 Gene Ontology cellular-component term for nuclear chromosome.
DOI:10.1101/gad.1144403 De Wulf, McAinsh and Sorger 2003, Hierarchical assembly of the budding yeast kinetochore from multiple subcomplexes, Genes & Development.
DOI:10.1534/genetics.112.145276 Biggins 2013, The composition, functions, and regulation of the budding yeast kinetochore, Genetics.

Curation history

2026-09-15T12:27:34Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-15T12:28:48Z codex · EXPANDED_RECORD — Added GO hierarchy and parthood, four reviewed label-only COMA subunits, a Saccharomyces cerevisiae taxonomic example, inner-to-outer kinetochore bridging function, DOI/GO evidence, a nonmechanistic COMA bridge graph, and a Ctf19/CCAN boundary TODO.
2026-09-15T12:29:21Z codex · REFINED_GRAPH — Connected COMA to the centromeric DNA-proximal side of the inner-to-outer kinetochore bridge graph.
2026-09-15T12:39:25Z codex · FIX_DISCUSSION_ANCHORS — Attached the Ctf19/CCAN boundary TODO to concrete COMA component IDs.
2026-09-15T12:46:39Z codex · REVIEW_FIXES — Resolved #975 and #976 by giving the two COMA bridge edges side-specific predicates and adding a TODO for the GO exact-synonym Mcm1p/Mcm21p spelling mismatch.

Source: data/structures/other/coma_complex.yaml