Ribulose bisphosphate carboxylase large chain (cbbL) is a 473-residue protein from Halothiobacillus neapolitanus (strain ATCC 23641 / c2). This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: O85040.
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The mean pLDDT of this model is 97.2 (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 | 97% |
| 70 to 90 | Confident: backbone generally right | 2% |
| 50 to 70 | Low: treat with caution | 1% |
| Below 50 | Very low: often disordered regions | 1% |
What pLDDT means and how to read it
RuBisCO catalyzes two reactions: the carboxylation of D-ribulose 1,5-bisphosphate, the primary event in carbon dioxide fixation, as well as the oxidative fragmentation of the pentose substrate. Both reactions occur simultaneously and in competition at the same active site (By similarity) (PubMed:18258595, PubMed:18974784, Ref.3). There are estimated to be 270 RuBisCO heterohexadecamers per carboxysome (Ref.6)
Heterohexadecamer of 8 large chains and 8 small chains (By similarity) (Ref.14). Forms a CsoS2-CsoS1-RuBisCO complex (Probable). The N-terminus (residues 1-136) interacts with shell proteins CsoS1A, CsoS1B and CsoS1C (PubMed:30305640). Holo-RuBisCO interacts with the N-terminal repeats of CsoS2; binding is sensitive to ionic strength. A fusion of a single N-terminal repeat to the C-terminus of…
Carboxysome
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 1SVD | X-ray | 1.8 Å | A=1-473 |
| 7SMK | EM | 1.98 Å | A=2-473 |
| 7SNV | EM | 2.07 Å | A=2-473 |
| 6UEW | X-ray | 2.4 Å | A/C/E/G=2-473 |
| 7ZBT | EM | 3.3 Å | A/B/C/D/E/F/G/H=1-473 |
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