Autoradiograms of chase reactions monitoring A, RBX1- or B, RBX2-mediated 32P-NEDD8 transfer from UBE2F (left) and UBE2M (right) to the indicated CULCTD. C, Autoradiograms for chase reactions monitoring 32P-NEDD8 transfer from UBE2F or UBE2M to the indicated CULCTD mediated by RBX chimeras harboring the indicated N-terminus/RBX2 RING (top panel), and the indicated N-terminus/RBX1 RING (bottom panel). D, UBE2F reactions as in A and B, except with RBX2(Ile52Ala)-CUL5 (left) and wild-type RBX2 in complex with non-NEDD8ylatable CUL5CTD(K724R) as indicated (right). E, UBE2M reactions as in A and B, except with RBX2(Ile44Ala)-CUL1 (left) and wild-type RBX1 in complex with non-NEDD8ylatable CUL1CTD(K720R) as indicated (right).