Coimmunoprecipitation of WT-Vif/Chim3 heterodimers. A total of 500 μg cellular lysates derived from HEK-293T cells cotransfected with the tagged Vifs-expressing constructs was immunoprecipitated (IP) with the anti-HA Ab and then immunoblotted with either the anti-myc or the anti-HA Abs, as indicated. The WT-Vif and Chim3 homodimers were loaded as positive controls of the coimmunoprecipitation, and the input WCE (40 μg) as positive control of the Western blot.