Complement C3 (C3) is a 1663-residue protein from Homo sapiens. This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: P01024.
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The mean pLDDT of this model is 79.8 (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 | 23% |
| 70 to 90 | Confident: backbone generally right | 58% |
| 50 to 70 | Low: treat with caution | 14% |
| Below 50 | Very low: often disordered regions | 5% |
What pLDDT means and how to read it
Precursor of non-enzymatic components of the classical, alternative, lectin and GZMK complement pathways, which consist in a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system
In absence of complement activation, the C3 precursor is first processed by the removal of 4 Arg residues, forming two chains, beta and alpha, linked by a disulfide bond
Secreted, Cell surface
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 2WY7 | X-ray | 1.7 Å | A=996-1303 |
| 2WY8 | X-ray | 1.7 Å | A=996-1303 |
| 7UE9 | X-ray | 1.75 Å | C=994-1303 |
| 1C3D | X-ray | 1.8 Å | A=996-1287 |
| 6RMT | X-ray | 2.0 Å | A/B=996-1303 |
| 7BAG | X-ray | 2.0 Å | A=23-667, B=749-1663 |
| 1GHQ | X-ray | 2.04 Å | A=996-1300 |
| 3D5R | X-ray | 2.1 Å | A/B=996-1287 |
| 3OXU | X-ray | 2.1 Å | A/B/C=996-1303 |
| 4I6O | X-ray | 2.14 Å | A=672-748 |
| 4ONT | X-ray | 2.15 Å | A/B/C=996-1303 |
| 2GOX | X-ray | 2.2 Å | A/C=996-1287 |
| 4ZH1 | X-ray | 2.24 Å | A/B/C=996-1303 |
| 4HW5 | X-ray | 2.25 Å | A/B=672-748 |
| 3D5S | X-ray | 2.3 Å | A/B=996-1287 |
| 2XQW | X-ray | 2.31 Å | A/B=996-1287 |
| 6S0B | X-ray | 2.31 Å | C=1517-1663 |
| 9N1Z | X-ray | 2.31 Å | A/C=996-1287 |
| 3RJ3 | X-ray | 2.35 Å | A/B/C=996-1303 |
| 2A74 | X-ray | 2.4 Å | A/D=23-665, B/E=749-936, C/F=1321-1663 |
Showing 20 of 75 experimental structures (best resolution first).
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