Complement decay-accelerating factor (CD55) is a 381-residue protein from Homo sapiens. This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: P08174.
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The mean pLDDT of this model is 78.3 (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 | 65% |
| 70 to 90 | Confident: backbone generally right | 1% |
| 50 to 70 | Low: treat with caution | 5% |
| Below 50 | Very low: often disordered regions | 29% |
What pLDDT means and how to read it
This protein recognizes C4b and C3b fragments that condense with cell-surface hydroxyl or amino groups when nascent C4b and C3b are locally generated during C4 and c3 activation. Interaction of daf with cell-associated C4b and C3b polypeptides interferes with their ability to catalyze the conversion of C2 and factor B to enzymatically active C2a and Bb and thereby prevents the formation of C4b2a and C3bBb, the amplification convertases of the complement cascade (PubMed:7525274). Inhibits complement activation by destabilizing and preventing the formation of C3 and C5 convertases, which prevents complement damage (PubMed:28657829)
Monomer (major form) and non-disulfide-linked, covalent homodimer (minor form). Interacts with ADGRE5 (PubMed:11297558)
Cell membrane, Secreted
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 1H03 | X-ray | 1.7 Å | P/Q=161-285 |
| 1H04 | X-ray | 2.0 Å | P=161-285 |
| 1OK3 | X-ray | 2.2 Å | A/B=35-285 |
| 1OJV | X-ray | 2.3 Å | A/B=35-285 |
| 1OJW | X-ray | 2.3 Å | A/B=35-285 |
| 1OK2 | X-ray | 2.5 Å | A/B=35-285 |
| 1OJY | X-ray | 2.6 Å | A/B/C/D=35-285 |
| 1OK1 | X-ray | 2.6 Å | A/B=35-285 |
| 8K9T | EM | 2.66 Å | B=339-353 |
| 8K9R | EM | 2.68 Å | B=339-353 |
| 1H2P | X-ray | 2.8 Å | P=161-285 |
| 6LA5 | EM | 2.86 Å | E=161-285 |
| 1H2Q | X-ray | 3.0 Å | P=161-285 |
| 1OK9 | X-ray | 3.0 Å | A/B=35-285 |
| 1UOT | X-ray | 3.0 Å | P=161-285 |
| 6ILK | EM | 3.0 Å | E=94-285 |
| 7VY6 | EM | 3.02 Å | E=35-285 |
| 8B8R | EM | 3.1 Å | E=28-285 |
| 7VY5 | EM | 3.15 Å | E=98-220 |
| 7DO4 | X-ray | 3.2 Å | B=35-284 |
Showing 20 of 33 experimental structures (best resolution first).
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