Complement C4-B (C4B) is a 1744-residue protein from Homo sapiens. This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: P0C0L5.
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The mean pLDDT of this model is 83.4 (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 | 42% |
| 70 to 90 | Confident: backbone generally right | 45% |
| 50 to 70 | Low: treat with caution | 6% |
| Below 50 | Very low: often disordered regions | 7% |
What pLDDT means and how to read it
Precursor of non-enzymatic components of the classical, 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, circulates in blood as a disulfide-linked trimer of an alpha, beta and gamma chain
Secreted, Synapse, Cell projection, axon, Cell projection, dendrite, Cell surface
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 9U60 | EM | 2.9 Å | E=1-1744 |
| 9U5Z | EM | 3.1 Å | E=1-1744 |
| 9U61 | EM | 3.1 Å | E=1-1744 |
| 6YSQ | X-ray | 3.3 Å | A/B=20-675, E/F=1454-1744 |
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