Figure 10.

Ast1p mediates clustering of Pma1p during biosynthetic transport. PMA1 (L3852) and PMA1[AST1CEN] cells were pulse-labeled with [³⁵S]methionine for 10 min at 24°C and chased for 0, 15, or 30 min at the same temperature. Cells lysates were subjected to SDS/TX100 velocity gradient fractionation as in Figure 9. Fractions 1-2-3 (A), 4-5-6 (B), and 7-8-9 (C) were pooled and Pma1p and Ast1-myc were immunoprecipitated and analyzed as before. Pma1p becomes oligomerized already after 15 min of chase. Note that the slower migrating form of Pma1p (see Figure 9) is not preserved during immunoprecipitation.