Figure 9.

20S complex formation on membranes is more efficient than in solution. (A) Coated vesicle-derived membranes were incubated as standard without (lanes 1, 3, 5, and 7) or with (lanes 2, 4, 6, and 8) detergent and then UV-irradiated. Increasing amounts of unlabeled α-SNAP were present, as indicated. The appearance of a 75-kDa, α-SNAP-dependent cross-link (lanes 3–6) is indicated by an asterisk. (B) Coated vesicle-derived membranes (one fifth of that used in panel A) were incubated with radiolabeled α-SNAP and increasing amounts of unlabeled α-SNAP. Formation of 20S complexes containing radiolabeled α-SNAP was assayed as described.