Functional analysis of CrUbcE2_1. Total E. coli proteins isolated from the BL21 strain were transformed with pRanGAP1-C2 (lane 1), pT-E1E2S1 and pRanGAP1-C2 (lane 2), pT-E1E2S1ΔE2 and pRanGAP1-C2 (lane 3), and pT-E1E2S1ΔE2, pRanGAP1-C2, and pGEX4T1-CrUbcE2-1 (lane 4), respectively, and incubated under conditions allowing Ubc9 conjugation. Top: SUMOylated RanGAP1-C2 (A) and nonSUMOylated RanGAP1-C2 (B) detected on immunoblots with anti-6× His antibody. Bottom: GST-CrUbcE2_1 (C) detected with anti-GST antibody. WB, Western blot.