Complement component C8 alpha chain (C8A) is a 584-residue protein from Homo sapiens. This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: P07357.
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The mean pLDDT of this model is 78.7 (confident 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 | 30% |
| 70 to 90 | Confident: backbone generally right | 49% |
| 50 to 70 | Low: treat with caution | 8% |
| Below 50 | Very low: often disordered regions | 13% |
What pLDDT means and how to read it
Component of the membrane attack complex (MAC), a multiprotein complex activated by the complement cascade, which inserts into a target cell membrane and forms a pore, leading to target cell membrane rupture and cell lysis (PubMed:17872444, PubMed:22832194, PubMed:26841837, PubMed:27052168, PubMed:30552328, PubMed:7440581). The MAC is initiated by proteolytic cleavage of C5 into complement C5b in response to the classical, alternative, lectin and GZMK complement pathways (PubMed:17872444, PubMed:30552328, PubMed:39914456, PubMed:39814882, PubMed:7440581). The complement pathways consist in a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that…
Heterotrimer of 3 chains: alpha (C8A), beta (C8B) and gamma (C8G); the alpha and gamma chains are disulfide bonded (PubMed:17692377, PubMed:18440555, PubMed:21454577). Component of the membrane attack complex (MAC), composed of complement C5b, C6, C7, C8A, C8B, C8G and multiple copies of the pore-forming subunit C9 (PubMed:22832194, PubMed:26841837, PubMed:27052168, PubMed:30552328,…
Secreted, Target cell membrane
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 2QOS | X-ray | 1.81 Å | A=188-198 |
| 2RD7 | X-ray | 2.15 Å | A=133-492 |
| 2QQH | X-ray | 2.5 Å | A=133-492 |
| 3OJY | X-ray | 2.51 Å | A=31-584 |
| 8B0F | EM | 3.0 Å | E=1-584 |
| 7NYD | EM | 3.3 Å | E=31-584 |
| 8B0G | EM | 3.3 Å | E=1-584 |
| 8B0H | EM | 3.3 Å | E=1-584 |
| 7NYC | EM | 3.5 Å | E=31-584 |
| 6H03 | EM | 5.6 Å | F=31-584 |
| 6H04 | EM | 5.6 Å | F=31-584 |
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