FIG. 4.

Translocation of CTA1-CVIM in the parental and class 5 mutant cell lines from the ER to the cytosol. Cells transfected with CTA1-CVIM were incubated with 150 μCi of [³⁵S]methionine per ml for 1 h and were then solubilized in ice-cold Triton X-114. After warming to 37°C, aqueous (i.e., ER lumen) and detergent (i.e., cytosolic) phases of the cell extracts were separated by centrifugation. Both phases were subjected to anti-CTA immunoprecipitation, and SDS-PAGE with PhosphorImager analysis was used to visualize and quantitate the immunoisolated material. The cytosolic pools of CTA1-CVIM are expressed as percentages of the total CTA1-CVIM found in both aqueous (Aqu.)- and detergent (Det.)-phase samples. Results represent the means ± standard errors of at least four independent experiments for each cell line.