Zinc finger region of ARIP3 is required for the recruitment of other sumoylated proteins. (A) FLAG-tagged wild-type ARIP3, ARIP3Δ347-418, ARIP3Δ467-487, and ARIP3Δ346-475 were coexpressed in COS-1 cells without or with pSG5-His-SUMO-1 as described for Fig. 4. Cells were lysed in RIPA-1 buffer, and samples from the lysate were immunoblotted with the anti-FLAG antibody. (B) Expression vectors encoding EGFP, EGFP-ARIP3 (341-418), or EGFP-ARIP3 (341-490) were cotransfected into COS-1 cells without or with pSG5-His-SUMO-1. Cells were lysed in RIPA-1 buffer, and lysates were immunoblotted with an antibody against GFP. (C) The rest of the lysates from panel A were immunoprecipitated (IP) with the anti-FLAG antibody, and immunoprecipitates were immunoblotted with the anti-SUMO-1 antibody. (D) The rest of the lysates from panel B were immunoprecipitated with the anti-GFP antibody, and immunoprecipitates were immunoblotted with the anti-SUMO-1 antibody. WB, Western blotting.