FIGURE 4.
Release from BiP is not required for substrate binding to Grp170. COS-1 cells were transfected with NS-1 LC, Grp170, and BiPWT or BiPT37G as indicated. Subsequently cells were pulse-labeled with [35S]cysteine/methionine for 0.5 h, chased for 1 h and lysed in the presence of ATP (A) or apyrase (B). The lysate was equally divided and immunoprecipitated with the indicated immune reagents. For quantitative analysis the signal of NS-1 LC bound to Grp170, BiP or BiPT37G was divided by the value for NS-1 LC obtained with κLC immunoprecipitations (n = 4 ± S.E., wild-type BiP, and n = 8 ± S.E., BiPT37G; n.s.: not significant).