B-lymphocyte antigen CD19 (CD19) is a 556-residue protein from Homo sapiens. This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: P15391.
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The mean pLDDT of this model is 62.2 (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 | 24% |
| 70 to 90 | Confident: backbone generally right | 19% |
| 50 to 70 | Low: treat with caution | 12% |
| Below 50 | Very low: often disordered regions | 45% |
What pLDDT means and how to read it
Functions as a coreceptor for the B-cell antigen receptor complex (BCR) on B-lymphocytes (PubMed:29523808). Decreases the threshold for activation of downstream signaling pathways and for triggering B-cell responses to antigens (PubMed:1373518, PubMed:16672701, PubMed:2463100). Activates signaling pathways that lead to the activation of phosphatidylinositol 3-kinase and the mobilization of intracellular Ca(2+) stores (PubMed:12387743, PubMed:16672701, PubMed:9317126, PubMed:9382888). Is not required for early steps during B cell differentiation in the blood marrow (PubMed:9317126). Required for normal differentiation of B-1 cells (By similarity). Required for normal B cell differentiation…
Interacts with CR2/CD21 (PubMed:1702139). Part of a complex composed of CD19, CR2/CD21, CD81 and IFITM1/CD225 in the membrane of mature B-cells (PubMed:1383329). Interacts directly with CD81 (via the second extracellular domain); this interaction is initiated early during biosynthesis in the ER/pre-Golgi compartments and is essential for trafficking and compartmentalization of CD19 receptor on…
Cell membrane, Membrane raft
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 6AL5 | X-ray | 3.0 Å | A=21-277 |
| 7URV | EM | 3.05 Å | C=21-277 |
| 7URX | EM | 3.4 Å | C=1-278 |
| 7JIC | EM | 3.8 Å | A=20-327 |
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