Polymerase acidic protein (PA) is a 716-residue protein from Influenza A virus. This is its AlphaFold structure prediction, created 3 Sept 2026. UniProt accession: P03433.
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The mean pLDDT of this model is 83.6 (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 | 37% |
| 70 to 90 | Confident: backbone generally right | 49% |
| 50 to 70 | Low: treat with caution | 11% |
| Below 50 | Very low: often disordered regions | 2% |
What pLDDT means and how to read it
Plays an essential role in viral RNA transcription and replication by forming the heterotrimeric polymerase complex together with PB1 and PB2 subunits. The complex transcribes viral mRNAs by using a unique mechanism called cap-snatching. It consists in the hijacking and cleavage of host capped pre-mRNAs. These short capped RNAs are then used as primers for viral mRNAs. The PB2 subunit is responsible for the binding of the 5' cap of cellular pre-mRNAs which are subsequently cleaved after 10-13 nucleotides by the PA subunit that carries the endonuclease activity
Influenza RNA polymerase is composed of three subunits: PB1, PB2 and PA. Interacts (via C-terminus) with PB1 (via N-terminus)
Host cytoplasm, Host nucleus
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 7XGC | X-ray | 1.6 Å | A=1-50, A=73-197 |
| 5JHT | X-ray | 1.75 Å | A=1-50, A=73-197 |
| 4ZI0 | X-ray | 1.8 Å | A=1-50, A=73-197 |
| 4ZQQ | X-ray | 1.8 Å | A=1-50, A=73-197 |
| 4YYL | X-ray | 1.91 Å | A=1-50, A=73-197 |
| 5FDG | X-ray | 2.1 Å | A=1-50, A=73-197 |
| 5I13 | X-ray | 2.15 Å | A=1-50, A=73-197 |
| 2ZNL | X-ray | 2.3 Å | A=239-716 |
| 4ZHZ | X-ray | 2.5 Å | A=1-50, A=73-197 |
| 5FDD | X-ray | 2.51 Å | A=1-50, A=73-197 |
| 5JHV | X-ray | 2.75 Å | A/B=1-50, A/B=73-197 |
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