Table 1.
Phases of the Translation Elongation Cycle.
| Intermediate | Stage | Ternary Complex | EF-G | A Site | P Site | E Site | PDB | Proofreading | |||
|---|---|---|---|---|---|---|---|---|---|---|---|
| (Figure 1) | ASL | CCA/PTC | ASL | CCA/PTC | ASL | CCA | |||||
| A | aa-tRNA.EF-Tu.GTP (free) | empty | empty | P site | A2451, C2452, U2585, G2252:C74, G2251:C75, CCA-peptide | E site | E site U2431, A2432 | 1TTT | |||
| B | Cplx 1 | aa-tRNA.EF-Tu.GTP (bound) | A/T, open | empty | P site | A2451, C2452, U2585, G2252:C74, G2251:C75, CCA-peptide | E site | E site U2431, A2432 | 5UYK | ||
| Cplx 2 | aa-tRNA.EF-Tu.GTP (bound) | A/T, latched | empty | P site | A2451, C2452, U2585, G2252:C74, G2251:C75, CCA-peptide | E site | E site U2431, A2432 | 5UYL | !! | ||
| C | Cplx 3 | aa-tRNA.EF-Tu.GTP (bound) | A/T, latched | empty | P site | A2451, C2452, U2585, G2252:C74, G2251:C75, CCA-peptide | E site | E site U2431, A2432 | 5UYM | !! | |
| D | Elbow | aa-tRNA.EF-Tu.GDP (bound) | EA, latched | empty | P site | A2451, C2452, U2585, G2252:C74, G2251:C75, CCA-peptide | E site | E site U2431, A2432 | !!!! | ||
| E | CCA | EF-G.GTP (binds) | A, latched | CCA-aa, C75:G2553 | P site | A2451, C2452, U2585, G2252:C74, G2251:C75, CCA-peptide | E site | E site U2431, A2432 | 5IBB, 4WPO | ||
| F | EF-G.GTP | A, latched | CCA-peptide, C75:G2553 | P site | A2451, C2452, U2585, G2252:C74, G2251:C75, CCA | E site | E site U2431, A2432 | ||||
| G | pre | EF-G.GDP | ap, open | (CCA-peptide, C75:G2553) | empty | (ap/A<-->ap/ap tRNA-peptide) | pe | pe/E tRNA: U2431, A2432 | 4W29, 4V5M | ||
| pre/post | EF-G.GDP | ap, open | (CCA-peptide, C75:G2553) | empty | (ap/A<-->ap/ap tRNA-peptide) | pe | pe/E tRNA: U2431, A2432 | ||||
| H | post | EF-G.GDP | ap, open | (CCA-peptide, C75:G2553) | empty | (ap/A<-->ap/ap tRNA-peptide) | pe | pe/E tRNA: U2431, A2432 | 4V5N, 5OT7 | ||
| latch: 30S: S12, 16S: G530~A1492, A1493; 23S: A1913 | |||||||||||
Cplx: complex; elbow or EA: elbow accommodation; CCA: CCA accommodation. Steps that are most important for translational accuracy are indicated with exclamation points.