Figure 3.

Time course of modification of ppαF. (A) Radiolabeled full-length ppαF with a cysteine at position 56 was translocated into rough microsomes. The samples were centrifuged resulting in P and S fractions. The membranes were incubated with 50 μM MB for different time periods on ice. One-half of the samples was analyzed after TCA precipitation; the other was incubated with streptavidin beads and the bound material was analyzed. ppαF, gppαF, pro-α-factor without or with three carbohydrate chains, respectively. (B) Quantification of the experiment in A.