Importin subunit alpha (SRP1) is a 542-residue protein from Saccharomyces cerevisiae (strain ATCC 204508 / S288c). This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: Q02821.
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The mean pLDDT of this model is 86.1 (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 | 76% |
| 70 to 90 | Confident: backbone generally right | 4% |
| 50 to 70 | Low: treat with caution | 5% |
| Below 50 | Very low: often disordered regions | 15% |
What pLDDT means and how to read it
Functions in nuclear protein import as an adapter protein for importin beta nuclear receptors (PubMed:10913188). Binds specifically and directly to substrates containing either a simple or bipartite NLS motif (PubMed:10745017). Promotes docking of import substrates to the nuclear envelope (PubMed:8521485). Together with importin beta KAP95, mediates nuclear import of transcription factor GCN4 (PubMed:14648200). Together with tethering factor STS1, targets the proteasome to the nucleus (PubMed:10913188, PubMed:21075847)
Forms a complex with an importin beta subunit. In the nucleus, interacts with NUP2 which accelerate release of NLSs, NUP2 is subsequently displaced by CSE1:RanGTP which mediates re-export and recycling. Interacts with HEH2, SHE2, and STS1
Cytoplasm, perinuclear region
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 1WA5 | X-ray | 2.0 Å | B=1-530 |
| 1EE4 | X-ray | 2.1 Å | A/B=87-509 |
| 1BK5 | X-ray | 2.2 Å | A/B=89-510 |
| 5H2X | X-ray | 2.2 Å | A=88-510 |
| 4XZR | X-ray | 2.25 Å | B=88-509 |
| 1EE5 | X-ray | 2.4 Å | A=87-510 |
| 4PVZ | X-ray | 2.5 Å | A/B=88-509 |
| 5H2W | X-ray | 2.5 Å | A/C=88-510 |
| 1UN0 | X-ray | 2.6 Å | A/B=88-530 |
| 2C1T | X-ray | 2.6 Å | A/B=88-541 |
| 5T94 | X-ray | 2.63 Å | B=1-542 |
| 1BK6 | X-ray | 2.8 Å | A/B=89-510 |
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