Ras-related protein Rab-21 (RAB21) is a 225-residue protein from Homo sapiens. This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: Q9UL25.
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The mean pLDDT of this model is 82.0 (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 | 59% |
| 70 to 90 | Confident: backbone generally right | 17% |
| 50 to 70 | Low: treat with caution | 7% |
| Below 50 | Very low: often disordered regions | 17% |
What pLDDT means and how to read it
The small GTPases Rab are key regulators of intracellular membrane trafficking, from the formation of transport vesicles to their fusion with membranes. Rabs cycle between an inactive GDP-bound form and an active GTP-bound form that is able to recruit to membranes different sets of downstream effectors directly responsible for vesicle formation, movement, tethering and fusion (PubMed:18804435, PubMed:25648148, PubMed:31455601). RAB21 is involved in membrane trafficking control (PubMed:18804435, PubMed:25648148). During the mitosis of adherent cells, controls the endosomal trafficking of integrins which is required for the successful completion of cytokinesis (PubMed:18804435). Regulates…
Interacts with the cytoplasmic tail of integrins ITGA1, ITGA2, ITGA5, ITGA6, ITGA11 and ITGB1 (By similarity). Interacts with RABGEF1 (via VPS9 domain) (PubMed:17450153). Interacts with ANKRD27 (PubMed:16525121, PubMed:18477474). Interacts with VAMP7 (PubMed:25648148). Interacts (in GTP-bound form) with VAMP8 in response to starvation; the interaction probably regulates VAMP8 endolysosomal…
Endoplasmic reticulum membrane, Golgi apparatus, trans-Golgi network, Golgi apparatus membrane, Early endosome membrane, Cytoplasmic vesicle membrane, Cleavage furrow, Cell projection, neuron projection
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 1Z08 | X-ray | 1.8 Å | A/B/C/D=16-183 |
| 1YZT | X-ray | 2.05 Å | A/B=16-183 |
| 2OT3 | X-ray | 2.1 Å | B=16-183 |
| 1Z0I | X-ray | 2.33 Å | A=16-183 |
| 1YZU | X-ray | 2.5 Å | A/B=16-183 |
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