Exotoxin type C (speC) is a 235-residue protein from Streptococcus pyogenes serotype M18 (strain MGAS8232). This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: Q8NKX2.
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The mean pLDDT of this model is 90.8 (very high 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 | 86% |
| 70 to 90 | Confident: backbone generally right | 2% |
| 50 to 70 | Low: treat with caution | 2% |
| Below 50 | Very low: often disordered regions | 10% |
What pLDDT means and how to read it
Superantigen that acts as a causative agent of the symptoms associated with scarlet fever (PubMed:11163233, PubMed:1500157, PubMed:1987034, PubMed:9253413). Has been associated with streptococcal toxic shock-like disease and may play a role in the early events of rheumatic fever (PubMed:11163233, PubMed:1500157, PubMed:9253413). Superantigens cross-link major histocompatibility complex (MHC) class II and T-cell receptor (TCR) molecules, resulting in an overstimulation of T-cells associated with a massive release of pyrogenic and inflammatory cytokines (PubMed:11163233, PubMed:9253413)
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 1AN8 | X-ray | 2.4 Å | A=28-235 |
| 1KTK | X-ray | 3.0 Å | A/B/C/D=28-235 |
| 1HQR | X-ray | 3.2 Å | D=28-235 |
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