Binding of FAC to RED. (A) IP of FAC-RED complexes. COS-1 cells overexpressing FAC, RED, or a combination were radiolabeled with a mixture of 35S-cysteine and methionine, cytoplasmic lysates immunoprecipitated sequentially with anti-FAC antibody and protein A-agarose and analyzed by 10% SDS-PAGE and autoradiography. The same panel of unlabeled lysates was also analyzed by immunoblotting with anti-RED antibody. Twenty times as much lysate was used for binding to RED as that applied directly in the immunoblotting experiment. (B) FAC-bound and unbound forms of RED. Sequential IP of cytoplasmic lysates from COS-1 cells transfected with both FAC and RED shows that a fraction of the total intracellular pool of FAC and RED associate with each other. Relative molecular masses are shown.
