Seroatlas · Human Serome Atlas

MMAB

Corrinoid adenosyltransferase MMAB

Also known as: cblB, CFAP23, MMAB_HUMAN

Cross-references: UniProt · Ensembl · Human Protein Atlas · GeneCards · NCBI Gene

Protein identityUniProt · HPA

UniProt accession
Q96EY8
Gene
MMAB
Ensembl
ENSG00000139428
Chromosome
12
Canonical length
250 aa
Protein class
Disease related genes, Human disease related genes, Metabolic proteins, Predicted intracellular proteins
Subcellular location
Mitochondria
Quaternary structure
Homotrimer

OverviewNCBI Gene

This gene encodes a protein that catalyzes the final step in the conversion of vitamin B(12) into adenosylcobalamin (AdoCbl), a vitamin B12-containing coenzyme for methylmalonyl-CoA mutase. Mutations in the gene are the cause of vitamin B12-dependent methylmalonic aciduria linked to the cblB complementation group. Alternatively spliced transcript variants have been found. [provided by RefSeq, Apr 2011]

Canonical amino-acid sequenceUniProt

250 residues, UniProt reviewed canonical sequence.

>Q96EY8|MMAB
     1  MAVCGLGSRL GLGSRLGLRG CFGAARLLYP RFQSRGPQGV EDGDRPQPSS KTPRIPKIYT
    61  KTGDKGFSST FTGERRPKDD QVFEAVGTTD ELSSAIGFAL ELVTEKGHTF AEELQKIQCT
   121  LQDVGSALAT PCSSAREAHL KYTTFKAGPI LELEQWIDKY TSQLPPLTAF ILPSGGKISS
   181  ALHFCRAVCR RAERRVVPLV QMGETDANVA KFLNRLSDYL FTLARYAAMK EGNQEKIYMK
   241  NDPSAESEGL

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against MMAB can act on the native protein depends on physical access: surface and secreted proteins are reachable by circulating antibodies, intracellular proteins usually are not.

Antibody reachability
Intracellular
Secreted
No
Transmembrane segments
0
Mean surface accessibility (rSASA)
0.41
Highest tissue expression
105 nTPM

Expression across tissuesHPA

Tissue

  • liver: 105 nTPM
  • adrenal gland: 49 nTPM
  • kidney: 36 nTPM
  • spinal cord: 31 nTPM
  • heart muscle: 29 nTPM
  • esophagus: 28 nTPM

Single-cell type

  • hepatocytes: 220 nCPM
  • breast lactating cells: 202 nCPM
  • esophageal apical cells: 163 nCPM
  • esophageal suprabasal cells: 158 nCPM
  • epididymal principal cells: 146 nCPM
  • alveolar cells type 2: 127 nCPM

Immune cell

  • naive B-cell: 18 nTPM
  • gdT-cell: 15 nTPM
  • naive CD4 T-cell: 15 nTPM
  • naive CD8 T-cell: 15 nTPM
  • memory B-cell: 14 nTPM
  • MAIT T-cell: 12 nTPM

Brain region

  • white matter: 26 nTPM
  • medulla oblongata: 25 nTPM
  • pons: 23 nTPM
  • midbrain: 19 nTPM
  • spinal cord: 19 nTPM
  • thalamus: 18 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about MMAB.

Disease | AllUniProt

Conditions MMAB is implicated in, by any mechanism.

  • Methylmalonic aciduria, cblB type (MACB) MIM:251110

Disease | GeneticClinVar

110 pathogenic / likely-pathogenic of 597 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

Genetic constraint and essentialitygnomAD · DepMap

Does the body need this protein intact? Low LOEUF or a strong DepMap dependency means loss or blockade of the protein is likely to be felt.

gnomAD LOEUF (loss-of-function intolerance)
0.88
gnomAD pLI
0
gnomAD missense Z
-0.11
DepMap mean gene effect
0.03
DepMap dependency class
selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 4% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

  • Cobalamin adenosyltransferase-like
  • Corrinoid adenosyltransferase, PduO-type
  • Cobalamin adenosyltransferase-like superfamily
  • Cobalamin adenosyltransferase

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads MMAB as an antibody target. Whether an autoantibody or antibody against MMAB could matter depends on whether native MMAB is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

MMAB is annotated as predominantly intracellular. Intracellular proteins are common autoantibody markers, becoming visible to the immune system after cell injury or altered processing, but are usually markers of disease rather than direct drivers.

Annotation status

The present source text does not explicitly label MMAB as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/MMAB. Study-independent annotations aggregated from UniProt, Human Protein Atlas, PubMed, IEDB, Pfam, InterPro, Gene Ontology, AlphaFold, gnomAD, DepMap, ClinVar, TCGA. Catalog release seroatlas-reviewed-human-uniprot-20260313.

Seroatlas is the reference for exploring autoantibody and antibody serology at the human-protein level: the autoreactome and human serome, multiplex serology (HuProt, HuScan, VirScan, PhIP-Seq).

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