Tol-Pal system protein TolB (tolB) is a 430-residue protein from Escherichia coli (strain K12). This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: P0A855.
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The mean pLDDT of this model is 94.3 (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 | 90% |
| 70 to 90 | Confident: backbone generally right | 4% |
| 50 to 70 | Low: treat with caution | 1% |
| Below 50 | Very low: often disordered regions | 4% |
What pLDDT means and how to read it
Part of the Tol-Pal system, which plays a role in outer membrane invagination during cell division and is important for maintaining outer membrane integrity (PubMed:17233825). TolB occupies a key intermediary position in the Tol-Pal system because it communicates directly with both membrane-embedded components, Pal in the outer membrane and TolA in the inner membrane (PubMed:19696740). The Tol-Pal system is also required for polar localization of chemoreceptors clusters (PubMed:24720726). The system also appears to be required for the activity of several outer membrane-localized enzymes with cell wall remodeling activity (PubMed:32152098). Is involved in the uptake of some colicins A…
The Tol-Pal system is composed of five core proteins: the inner membrane proteins TolA, TolQ and TolR, the periplasmic protein TolB and the outer membrane protein Pal. They form a network linking the inner and outer membranes and the peptidoglycan layer (PubMed:17233825). TolB forms homodimers (PubMed:11994151). Interacts with the peptidoglycan-associated lipoprotein Pal and with the C-terminal…
Periplasm
Compare the prediction with experimentally determined structures of the same protein:
| PDB ID | Method | Resolution | Chains and residues |
|---|---|---|---|
| 2HQS | X-ray | 1.5 Å | A/B/D/F=23-430 |
| 2W8B | X-ray | 1.86 Å | A/B/D/F=22-430 |
| 1CRZ | X-ray | 1.95 Å | A=28-430 |
| 1C5K | X-ray | 2.0 Å | A=1-430 |
| 2IVZ | X-ray | 2.0 Å | A/B/C/D=1-430 |
| 3IAX | X-ray | 2.6 Å | A=1-430 |
| 7NST | EM | 3.7 Å | E=1-430 |
| 7NSU | EM | 4.7 Å | E=1-430 |
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