Seroatlas · Human Serome Atlas

B2M

Beta-2-microglobulin

Also known as: B2MG_HUMAN

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

Protein identityUniProt · HPA

UniProt accession
P61769
Gene
B2M
Ensembl
ENSG00000166710
Chromosome
15
Canonical length
119 aa
Protein class
Cancer-related genes, Disease related genes, Human disease related genes, Plasma proteins, Potential drug targets, Predicted secreted proteins, Transporters
Subcellular location
Golgi apparatus,Plasma membrane,Cytosol
Secretome location
Secreted to blood

OverviewNCBI Gene

This gene encodes a serum protein found in association with the major histocompatibility complex (MHC) class I heavy chain on the surface of nearly all nucleated cells. The protein has a predominantly beta-pleated sheet structure that can form amyloid fibrils in some pathological conditions. The encoded antimicrobial protein displays antibacterial activity in amniotic fluid. A mutation in this gene has been shown to result in hypercatabolic hypoproteinemia.[provided by RefSeq, Aug 2014]

Canonical amino-acid sequenceUniProt

119 residues, UniProt reviewed canonical sequence.

>P61769|B2M
     1  MSRSVALAVL ALLSLSGLEA IQRTPKIQVY SRHPAENGKS NFLNCYVSGF HPSDIEVDLL
    61  KNGERIEKVE HSDLSFSKDW SFYLLYYTEF TPTEKDEYAC RVNHVTLSQP KIVKWDRDM

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against B2M 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
Cell surface
Secreted
No
Transmembrane segments
0
Mean surface accessibility (rSASA)
0.36
Highest tissue expression
8,709 nTPM

Expression across tissuesHPA

Tissue

  • lymph node: 8,709 nTPM
  • spleen: 7,433 nTPM
  • bone marrow: 7,390 nTPM
  • lung: 5,807 nTPM
  • liver: 5,792 nTPM
  • urinary bladder: 5,381 nTPM

Single-cell type

  • enterocytes: 5,903 nCPM
  • kupffer cells: 5,841 nCPM
  • platelets: 5,107 nCPM
  • decidual stromal cells: 4,907 nCPM
  • plasma cells: 3,862 nCPM
  • cdc: 3,645 nCPM

Immune cell

  • total PBMC: 55,984 nTPM
  • neutrophil: 49,775 nTPM
  • basophil: 47,420 nTPM
  • eosinophil: 32,671 nTPM
  • T-reg: 29,216 nTPM
  • memory CD4 T-cell: 23,466 nTPM

Brain region

  • white matter: 817 nTPM
  • medulla oblongata: 769 nTPM
  • spinal cord: 663 nTPM
  • choroid plexus: 556 nTPM
  • thalamus: 541 nTPM
  • hypothalamus: 523 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about B2M.

Disease | AllUniProt

Conditions B2M is implicated in, by any mechanism.

Disease | GeneticClinVar

5 pathogenic / likely-pathogenic of 101 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

Disease | AutoantibodyPubMed

Conditions in which antibodies against B2M are reported. Each links to that disease's full target list.

ReferencesPubMed · IEDB

Publications for B2M from three distinct lines of evidence, kept separate because they answer different questions: whether antibodies are directed at the protein, whether a B-cell epitope has been mapped on it, and whether a T-cell epitope has. Each is labelled with its source.

Reference: AutoantibodyPubMed

18 publications

Show 13 more

Sources: PubMed — antigen-level antibody evidence from a custom retrieval. Records matching a controlled set of autoantibody terms (the MeSH descriptors Autoantibodies and Autoantigens, with title and abstract term variants) were obtained through NCBI E-utilities, and their titles and abstracts parsed for constructions that direct an antibody at a named protein rather than for co-occurrence. Captured names were resolved against UniProt nomenclature and each antigen adjudicated individually against the source text. Bibliographic records from PubMed and MeSH, U.S. National Library of Medicine; citation metrics from NIH iCite (Hutchins et al., PLoS Biology 2016). Titles link to PubMed; abstracts are not reproduced here. The NLM does not endorse this analysis.

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)
0.71
gnomAD pLI
0.56
gnomAD missense Z
0.81
DepMap mean gene effect
0.06
DepMap dependency class
none

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 5% 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

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of B2M in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads B2M as an antibody target. Whether an autoantibody or antibody against B2M could matter depends on whether native B2M is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

B2M is annotated at the cell surface, where native B2M is exposed to circulating antibodies and is a prime autoantibody target that could block, deplete, or overstimulate it.

Annotation status

The present source text does not explicitly label B2M as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/B2M. 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).

© 2026 · Seroatlas, Discover Oregon LLC · Terms of use

Loading the interactive Seroatlas protein explorer...