methyl coenzyme M reductase complex

GO:0044674 · Energy complex · Multiprotein complex · Proposed

Methyl coenzyme M reductase complex is a hexameric alpha2 beta2 gamma2 enzyme complex that catalyzes coenzyme B-dependent reduction of methyl-coenzyme M to methane during the terminal step of methanogenesis. [GO:0044674]

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
Methyl coenzyme M reductase, alpha subunit	Protein	part of	`InterPro:IPR016212`	mcrA	2	ESSENTIAL	Alpha subunit family present as two copies in the alpha2 beta2 gamma2 methyl coenzyme M reductase complex. `InterPro:IPR016212` InterPro IPR016212 is a family entry named Methyl coenzyme M reductase, alpha subunit and is annotated to coenzyme-B sulfoethylthiotransferase activity. `PDB:1MRO` RCSB maps PDB:1MRO polymer entity 1 to Methanothermobacter marburgensis str. Marburg methyl-coenzyme M reductase subunit alpha, UniProtKB:P11558, with two copies in the deposited complex.
Methyl-coenzyme M reductase, beta subunit	Protein	part of	`InterPro:IPR003179`	mcrB	2	ESSENTIAL	Beta subunit family present as two copies in the alpha2 beta2 gamma2 methyl coenzyme M reductase complex. `InterPro:IPR003179` InterPro IPR003179 is a family entry named Methyl-coenzyme M reductase, beta subunit and is annotated to coenzyme-B sulfoethylthiotransferase activity. `PDB:1MRO` RCSB maps PDB:1MRO polymer entity 2 to Methanothermobacter marburgensis str. Marburg methyl-coenzyme M reductase subunit beta, UniProtKB:P11560, with two copies in the deposited complex.
Methyl-coenzyme M reductase, gamma subunit	Protein	part of	`InterPro:IPR003178`	mcrG	2	ESSENTIAL	Gamma subunit family present as two copies in the alpha2 beta2 gamma2 methyl coenzyme M reductase complex. `InterPro:IPR003178` InterPro IPR003178 is a family entry named Methyl-coenzyme M reductase, gamma subunit and is annotated to coenzyme-B sulfoethylthiotransferase activity. `PDB:1MRO` RCSB maps PDB:1MRO polymer entity 3 to Methanothermobacter marburgensis str. Marburg methyl-coenzyme M reductase subunit gamma, UniProtKB:P11562, with two copies in the deposited complex.

Canonical examples

NCBITaxon:79929 Methanothermobacter marburgensis str. Marburg — Methanothermobacter strain that supplied all three alpha, beta, and gamma MCR polymer entities in the crystal structure deposited as PDB:1MRO. [PDB:1MRO]

Functions

coenzyme-B sulfoethylthiotransferase activity GO:0050524 — Methyl coenzyme M reductase catalyzes the reaction of coenzyme B with methyl-coenzyme M to form coenzyme M-coenzyme B heterodisulfide and methane.
- GO:0050524 GO:0050524 defines coenzyme-B sulfoethylthiotransferase activity as the reaction of coenzyme B with methyl-coenzyme M to form methane and coenzyme M-coenzyme B heterodisulfide.
- InterPro:IPR016212 InterPro annotates the methyl coenzyme M reductase alpha-subunit family to GO:0050524.
- InterPro:IPR003179 InterPro annotates the methyl-coenzyme M reductase beta-subunit family to GO:0050524.
- InterPro:IPR003178 InterPro annotates the methyl-coenzyme M reductase gamma-subunit family to GO:0050524.

Mechanism graphs

MCR reduces methyl-coenzyme M to methane (FUNCTION)

The alpha2 beta2 gamma2 methyl coenzyme M reductase complex catalyzes the final methanogenesis reaction, consuming coenzyme B and methyl-coenzyme M while releasing methane and coenzyme M-coenzyme B heterodisulfide.

Subject	Predicate	Object	Evidence
methyl coenzyme M reductase complex	enables	coenzyme-B sulfoethylthiotransferase activity	`GO:0044674` GO:0044674 defines methyl coenzyme M reductase as a hexameric complex involved in reduction of the coenzyme M-bound methyl group to methane. `GO:0050524` GO:0050524 defines the net coenzyme-B sulfoethylthiotransferase reaction catalyzed by methyl-CoM reductase.
Methyl coenzyme M reductase, alpha subunit	contributes to	coenzyme-B sulfoethylthiotransferase activity	`InterPro:IPR016212` InterPro IPR016212 is specific to methyl coenzyme M reductase alpha subunits and is annotated to GO:0050524. `PDB:1MRO` PDB:1MRO contains two copies of polymer entity 1, the M. marburgensis MCR alpha subunit.
Methyl-coenzyme M reductase, beta subunit	contributes to	coenzyme-B sulfoethylthiotransferase activity	`InterPro:IPR003179` InterPro IPR003179 is specific to methyl-coenzyme M reductase beta subunits and is annotated to GO:0050524. `PDB:1MRO` PDB:1MRO contains two copies of polymer entity 2, the M. marburgensis MCR beta subunit.
Methyl-coenzyme M reductase, gamma subunit	contributes to	coenzyme-B sulfoethylthiotransferase activity	`InterPro:IPR003178` InterPro IPR003178 is specific to methyl-coenzyme M reductase gamma subunits and is annotated to GO:0050524. `PDB:1MRO` PDB:1MRO contains two copies of polymer entity 3, the M. marburgensis MCR gamma subunit.
coenzyme B	is consumed by	coenzyme-B sulfoethylthiotransferase activity	`GO:0050524` GO:0050524 defines coenzyme-B sulfoethylthiotransferase activity as consuming coenzyme B.
methyl-coenzyme M	is consumed by	coenzyme-B sulfoethylthiotransferase activity	`GO:0050524` GO:0050524 defines coenzyme-B sulfoethylthiotransferase activity as consuming methyl-coenzyme M.
coenzyme-B sulfoethylthiotransferase activity	produces	methane	`GO:0050524` GO:0050524 records methane as a product of coenzyme-B sulfoethylthiotransferase activity.
coenzyme-B sulfoethylthiotransferase activity	produces	coenzyme M-coenzyme B heterodisulfide	`GO:0050524` GO:0050524 records coenzyme M-coenzyme B heterodisulfide as a product of coenzyme-B sulfoethylthiotransferase activity.

Evidence

GO:0044674 Gene Ontology cellular-component term for the methyl coenzyme M reductase complex.
GO:1990234 Gene Ontology cellular-component term for transferase complexes.
GO:0050524 Gene Ontology molecular-function term for coenzyme-B sulfoethylthiotransferase activity.
InterPro:IPR016212 InterPro family for the methyl coenzyme M reductase alpha subunit.
InterPro:IPR003179 InterPro family for the methyl-coenzyme M reductase beta subunit.
InterPro:IPR003178 InterPro family for the methyl-coenzyme M reductase gamma subunit.
DOI:10.1126/science.278.5342.1457 Ermler et al. 1997, Crystal structure of methyl-coenzyme M reductase: the key enzyme of biological methane formation, Science.
PMID:9367957 PubMed identifier for Ermler et al. 1997 as reported by RCSB PDB:1MRO and NCBI ESummary.
PDB:1MRO RCSB Protein Data Bank entry for the Methanothermobacter marburgensis str. Marburg alpha2 beta2 gamma2 methyl-coenzyme M reductase crystal structure from Ermler et al. 1997.

Curation history

2026-09-24T08:18:02Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-24T08:20:14Z codex · EXPANDED_RECORD — Added intracellular oxidoreductase parentage, alpha/beta/gamma MCR components grounded to exact InterPro families and PDB:1MRO polymer entities, a Methanothermobacter marburgensis canonical example, coenzyme-B sulfoethylthiotransferase activity evidence, and a compact whole-enzyme methane-production graph.
2026-09-24T08:21:48Z codex · CORRECTED_PARENTAGE — Replaced the inferred oxidoreductase and intracellular parentage with GO:1990234, the direct transferase-complex parent of GO:0044674 in GO basic, and narrowed the definition to avoid asserting oxidoreductase-class parentage.
2026-09-24T08:33:06Z codex · ADDRESS_REVIEW — #1469/#1470: removed unsupported broad archaeal wording from current definition and component prose, and added beta/gamma InterPro support to the coenzyme-B sulfoethylthiotransferase function evidence.

Source: data/structures/energy_complex/methyl_coenzyme_m_reductase_complex.yaml