FIG. 2.

Effect of the residue at position 17 on E5 dimerization. RIPA extracts of [¹⁴C]leucine-labelled C127 cells stably expressing representative E5 mutants were prepared as described in Materials and Methods. Extracts (normalized for incorporation of label) were immunoprecipitated with anti-E5 antibody, and the immunoprecipitates were resolved on a 15% SDS-polyacrylamide gel under nonreducing conditions. The gel was dried, and labeled proteins were detected by using a PhosphorImager. The letter at the top of each lane indicates the amino acid at position 17 of the mutant E5 protein. Extracts from cells infected with empty retrovirus vector (−) or the retrovirus expressing wild-type (WT) E5 protein are also shown, and the positions of monomeric and dimeric wild-type E5 protein are indicated. Sizes of molecular size markers (in kilodaltons) are shown on the left.