Beta-2-microglobulin (B2M) is a 119-residue protein from Homo sapiens. This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: P61769.
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The mean pLDDT of this model is 94.1 (very high overall). pLDDT is AlphaFold's per-residue confidence score from 0 to 100. In MolViewer, choose the B-factor color scheme to color the model by pLDDT, because AlphaFold stores it in the B-factor column.
| pLDDT band | Meaning | Share of residues |
|---|---|---|
| Above 90 | Very high: backbone and side chains are usually accurate | 83% |
| 70 to 90 | Confident: backbone generally right | 11% |
| 50 to 70 | Low: treat with caution | 6% |
| Below 50 | Very low: often disordered regions | 0% |
What pLDDT means and how to read it
Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system. Exogenously applied M.tuberculosis EsxA or EsxA-EsxB (or EsxA expressed in host) binds B2M and decreases its export to the cell surface (total protein levels do not change), probably leading to defects in class I antigen presentation (PubMed:25356553)
Heterodimer of an alpha chain and a beta chain. Beta-2-microglobulin is the beta-chain of major histocompatibility complex class I molecules. Polymers of beta 2-microglobulin can be found in tissues from patients on long-term hemodialysis. B2M alone (not in complex with HLA-I) interacts with M.tuberculosis EsxA (ESAT-6) and an EsxA-EsxB (CFP-10) complex; the tripartite complex can be detected in…
Secreted, Cell surface
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 4E0K | X-ray | 0.97 Å | A/B/C/D=78-83 |
| 1K5N | X-ray | 1.09 Å | B=21-119 |
| 3MRE | X-ray | 1.1 Å | B=21-119 |
| 2YXF | X-ray | 1.13 Å | A=21-119 |
| 8E2Z | X-ray | 1.13 Å | B=21-119 |
| 7NMR | X-ray | 1.15 Å | AAA=21-117 |
| 8ROP | X-ray | 1.15 Å | B=21-119 |
| 7R7W | X-ray | 1.17 Å | B=21-119 |
| 4U1M | X-ray | 1.18 Å | B=21-119 |
| 3CZF | X-ray | 1.2 Å | B=21-119 |
| 6Y26 | X-ray | 1.2 Å | B=21-119 |
| 7NMC | X-ray | 1.2 Å | AAA=21-119 |
| 7NMO | X-ray | 1.2 Å | AAA=21-119 |
| 7NMT | X-ray | 1.2 Å | AAA=21-119 |
| 6MT3 | X-ray | 1.21 Å | C=21-119 |
| 8EC5 | X-ray | 1.22 Å | B=21-119 |
| 4RMT | X-ray | 1.24 Å | A=21-119 |
| 7NN5 | X-ray | 1.24 Å | AAA=21-118 |
| 3IB4 | X-ray | 1.25 Å | A=21-119 |
| 6Y2A | X-ray | 1.25 Å | B=21-119 |
Showing 20 of 1345 experimental structures (best resolution first).
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