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Table 2 Cullin structures and cullin-RING E3 complex assembly

From: The cullin protein family

Protein E3 components Structures solved* Key recognition fold on adaptor Key determinants on cullin NTD
  Adaptor Substrate recognition RING    
CUL1 Skp1 F-box protein ROC1/Rbx1 CUL1-Rbx1-Skp1-F boxSkp2 [6]; Skp1-Skp2 [60] Skp1/BTB/POZ fold in Skp1 [6] CUL1 H2 and H5 helices [6]
CUL2 EloC/EloB VHL ROC1/Rbx1 No CUL2 structure; VHL-EloC-EloB [60] Skp1/BTB/POZ fold in EloC [6, 61] CUL2 H2 and H5 helices [14]
CUL3 BTB (adaptor-targeting) BTB (adaptor-targeting) ROC1/Rbx1 SPOP BTB-SBC [13] BTB [13]; 3-box [13] CUL3 H2 and H5 helices [62]
CUL4A DDB1 DCAF ROC1/Rbx1 DDB1-CUL4A-ROC1 [9]; DDB1-V protein [8] BPB in DDB1 [9] CUL4A H2 and H5 helices [9]; CUL4A amino-terminal extension [9]
CUL4B DDB1 DCAF ROC1/Rbx1 Not available BPB in DDB1 (predicted) CUL4B H2/H5 (predicted)
CUL5 EloC/EloB SOCS protein ROC2/Rbx2 CUL5CTD-Rbx1 [37]; SOCS2- EloC-EloB [63]; HIV Vif-EloC-EloB [16] Skp1/BTB/POZ fold in EloC [6, 61] CUL5 H2 and H5 helices [64]; CUL5 loop 2 (amino acids 51 to 60) [16]; CUL5 loop 5 (amino acids 118 to 134) [16]
CUL7 Skp1 Fbw8 ROC1/Rbx1 CUL7 CPH-p53 TD [65] Skp1/BTB/POZ fold in Skp1 (predicted) Unknown
PARC Unknown Unknown Unknown Not available Unknown Unknown
  1. *Crystal structures of CRL complexes were solved with recombinant human proteins.