FIG. 4.

Analysis of GP₅-M heterodimerization in BHK-21 cells transfected with wt EAV and a selection of mutants. Protein synthesis in transfected cells was³⁵S labeled from 10 to 13 posttransfection, and immunoprecipitations were carried out with antisera recognizing GP₅ (left side of panels) or M (right side of panels) of EAV. The immunoprecipitates were divided into two aliquots, which were analyzed under nonreducing conditions (A) or under reducing conditions (B), which have been described to disrupt the GP₅-M disulfide bond. In each lane, the relevant bands (see the text) are boxed. The sizes of GP₅ and the GP₅-M complex in the assay under nonreducing conditions are variable, depending on the presence of the 80.4 deletion in GP₅ (see the text). Constructs: lanes a, pA45 (wt); lanes b, pA45/C34S (GP₅ mutant); lanes c, pA45/C8S (M protein mutant); lanes d, pA45-80.4 (pseudorevertant); lanes e, pA45-80.4/C34S (pseudorevertant with Cys-34-to-Ser mutation in GP₅); lanes f, mock transfection; lanes g, control infection with wt EAV (MOI 10).