Figure 5.

Sec61p, Sec62p, Sec63p, Sec71p, and Sec72p all interact with precursor proteins in the absence of ATP; these interactions are dependent on an intact signal sequence and are altered in sec61 mutant membranes. Radiolabeled ppαf wild-type or m3-mutant precursor (300,000 cpm and 200 μg microsomal protein per immunoprecipitation) were incubated with the indicated membranes either in the presence (filled bars) or absence (hatched bars) of ATP followed by crosslinking with DSP and immunoprecipitation using antibodies against the indicated Sec proteins. Each bar is the average of two separate experiments.