Table 3.
Key interactions in structurally characterized E2:E3 complexes
| E2:E3 Complex [PDB:ID Code] | ||||
| Interaction E2: E3 | Cbl:UbcH7 [PDB:1FBV] | CNOT4:UbcH5 [PDB:1UR6] | CHIP:UbcH5 [PDB:2OXQ] | CHIP:Ubc13 [PDB:2C2V] |
| E2-α1: E3-L1 | ||||
| Arg:mainchain | R6:K382O precedes I383) | R5:P15O precedes L16) | R5:I235O | R7:I235O |
| Arg:sidechain | R5:M18 | R5:F237 (stacking) | R7:F237 (stacking) | |
| salt bridges | K4:E19/K4:E13 K8:E13 | R14:D229 | ||
| sidechain: mainchain | K8:F237O | K10:F237O | ||
| E2-L4/L7: E3-α/L1/L2 | ||||
| hydrophobic | P62/F63/P97/A98:I383/W408/P417/F418 | P61/F62/P95/A96:L16/I45/E49/L52/P54 | P61/F62/P95/A96:I235/H260/V264/P269/V270 | P63/M64/P97/A98:I235/H260/R263/V264/P269/V270 |
| E2-L4:E3-α polar | F62:R44 (stacking) Q92: E49 | F62:R263 (stacking) | ||
| E2-L4:E3-α salt bridges | D59:R44 K68: D48/E49 | |||
| E2-L7: E3-L2 polar | ||||
| S-P-A:mainchain | A98N:P417O K96:F418O | S96:P54O | S94:P269O | S96:P269O |
| mainchain:Arg | E93O:R420 | Q92O:R57 | Q92O:R272 | K94O:R272 |
Key interactions observed in structures of E2:E3 complexes [22, 30, 34]. The CNOT4:UbcH5 complex structure was not solved explicitly but modeled based on NMR structures of CNOT4 and UbcH5 and on experimental restraints derived from NMR data and mutagenesis [34].