Prosaposin (PSAP) is a 524-residue protein from Homo sapiens. This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: P07602.
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The mean pLDDT of this model is 73.8 (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 | 18% |
| 70 to 90 | Confident: backbone generally right | 50% |
| 50 to 70 | Low: treat with caution | 12% |
| Below 50 | Very low: often disordered regions | 21% |
What pLDDT means and how to read it
Saposins are specific low-molecular mass non-enzymatic glycoproteins that act as activator proteins for lysosomal sphingolipid-degrading enzymes, facilitating the hydrolysis of sphingolipids by extracting lipid substrates from membranes and presenting them to their respective enzymes. They are derived from a common precursor protein, prosaposin, which is proteolytically cleaved to yield four homologous proteins (saposin A, B, C, and D), each with distinct but partially overlapping lipid and enzyme specificities
Prosaposin exists as a roughly half-half mixture of monomers and disulfide-linked dimers (PubMed:21835174). Monomeric prosaposin interacts (via C-terminus) with sortilin/SORT1, the interaction is required for targeting to lysosomes (PubMed:14657016, PubMed:22431521). Interacts with GRN; facilitates lysosomal delivery of progranulin from the extracellular space and the biosynthetic pathway…
Lysosome, Secreted
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 3BQP | X-ray | 1.3 Å | A/B=405-484 |
| 9I63 | X-ray | 1.65 Å | A/B=405-486 |
| 4UEX | X-ray | 1.8 Å | A/B=60-142 |
| 4DDJ | X-ray | 1.9 Å | A=60-140 |
| 2DOB | X-ray | 2.0 Å | A=58-140 |
| 3BQQ | X-ray | 2.0 Å | A/B/C/D=405-484 |
| 2RB3 | X-ray | 2.1 Å | A/B/C/D=407-484 |
| 4V2O | X-ray | 2.13 Å | A/B/C=195-273 |
| 1N69 | X-ray | 2.2 Å | A/B/C=195-273 |
| 6SLR | X-ray | 2.38 Å | A/B/C=195-272 |
| 2GTG | X-ray | 2.4 Å | A=311-391 |
| 2QYP | X-ray | 2.45 Å | A/B=311-392 |
| 2R0R | X-ray | 2.5 Å | A/B=407-484 |
| 2R1Q | X-ray | 2.5 Å | A=407-484 |
| 2Z9A | X-ray | 2.5 Å | A/B=311-389 |
| 9AXG | X-ray | 2.68 Å | A/B=195-273 |
| 8EQU | EM | 2.8 Å | C/F=60-140 |
| 9AVS | X-ray | 3.53 Å | C=195-273 |
| 1M12 | NMR | A=311-390 | |
| 1SN6 | NMR | A=311-390 |
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