FIG. 1.

Proteolysis of reticulocyte lysate-synthesized Pr55^gag with HIV-1 protease. (A) Pr55^gag was synthesized in reticulocyte lysates as described in Materials and Methods, bound to COS-1 plasma membranes, and incubated with purified HIV-1 protease for 0, 5, or 120 min. The proteolytic products were fractionated by ultracentrifugation into soluble (S) and membrane bound (P), analyzed by SDS gel electrophoresis, and visualized with a PhosphorImager. Note the presence of p17MA in the membrane fraction and that of the p24-p2 intermediate in the soluble fraction at 5 min. After 2 h, 65% of p17MA has shifted to the soluble fraction. t, time. (B) Generation of p17MA and p24CA after treatment of Pr55^gag with HIV-1 protease as a function of time. The time dependence of p24CA and p17MA generation follows the same kinetics, since they arise from a common first cleavage intermediate of Pr55^gag, p39-p41. (C) Time course of p17MA and p24CA release from the membrane. The membrane dissociation of p17MA is slow in comparison to the release of p24CA.