Figure 3.

Prenylation of Myc-Rab1B proteins expressed in HEK-293 cells. Shown are the results of two separate metabolic labeling studies in which various Rab1B mutants were compared with the wild-type protein. Cultures were transfected with each of the indicated Myc-Rab1B constructs. Immediately after transfection, cells were incubated with [³H]MVA for 18 h. The Myc-tagged proteins were immunoprecipitated as described in MATERIALS AND METHODS. In the upper panels, one-tenth of each immunoprecipitate was subjected to SDS-PAGE and immunoblot analysis was performed using a primary antibody against Rab1B and goat anti-rabbit ¹²⁵I-labeled IgG as the secondary antibody. In the lower panels, the remainder of each immunoprecipitate was subjected to SDS-PAGE and fluorography to visualize the prenylated proteins. The ³H:¹²⁵I ratios were determined by densitometry and compared with the matching wt values as summarized in Table 1.