Immunoglobulin mu Fc receptor (FCMR) is a 390-residue protein from Homo sapiens. This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: O60667.
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The mean pLDDT of this model is 64.9 (low 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 | 31% |
| 70 to 90 | Confident: backbone generally right | 8% |
| 50 to 70 | Low: treat with caution | 19% |
| Below 50 | Very low: often disordered regions | 42% |
What pLDDT means and how to read it
High-affinity Fc receptor for immunoglobulin M (IgM), both secreted and membrane-bound IgM (PubMed:19858324, PubMed:22675200, PubMed:36949194, PubMed:37095205). Primarily regulates IgM transport and homeostasis. In lymphoid cells, enables exocytosis of membrane-bound IgM on the plasma membrane as well as endocytosis of IgM-antigen complexes toward lysosomes for degradation. In mucosal epithelium, mediates retrotranscytosis of antigen-IgM complexes across mucosal M cells toward antigen-presenting cells in mucosal lymphoid tissues (PubMed:21908732, PubMed:28230186). Triggers costimulatory signaling and mediates most of IgM effector functions involved in B cell development and primary immune…
Interacts (via Ig-like domain) with IGHM (via CH4/Cmu4 domain), both secreted and membrane-bound IgM; the interaction is glycan-independent and multivalent theoretically involving up to eight binding sites for the IgM pentamer
Cell membrane, Early endosome membrane, Golgi apparatus, trans-Golgi network membrane, Lysosome membrane, Secreted
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 7YTE | X-ray | 3.0 Å | C/D=18-124 |
| 8BPG | EM | 3.1 Å | A/B=18-251 |
| 7YSG | EM | 3.18 Å | R/S/U/V=18-124 |
| 7YTC | EM | 3.39 Å | R=18-124 |
| 8BPF | EM | 3.5 Å | I=18-251 |
| 8BPE | EM | 3.63 Å | I/M/N/O/P/Q/R/S=18-251 |
| 7YTD | EM | 3.71 Å | R/S/U/V=18-124 |
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