FIG. 2.

Biochemical fractionation of Yor1p. Wild-type cells were lysed with glass beads and fractionated over a sucrose gradient. Aliquots of each sucrose gradient fraction were precipitated with trichloroacetic acid, resuspended in Laemmli buffer, and electrophoresed by SDS-PAGE. The proteins were then transferred to nitrocellulose, and the resulting blot was probed with the indicated antisera. The relative positions of the light (top) and heavy (bottom) fractions of the sucrose gradient are indicated on the figure. Antisera employed listed on the right-hand side are as follows: Yor1p is the affinity-purified rabbit anti-Yor1p antibody used in Fig. 1, Pma1p corresponds to the plasma membrane ATPase protein (55), Sec61p is an integral membrane subunit of the translocon in the ER (59), Vps10p (also called Pep1p) is the Golgi apparatus- or prevacuole-localized carboxypeptidase Y (CPY) receptor (43), and Vph1p is the 100-kDa subunit of the vacuolar ATPase (42).