Figure 7.

Kinetics of degradation of newly synthesized mutant proinsulin and inhibition by lactacystin. To monitor the kinetics of degradation of newly synthesized mutant (Arg/Gly³²:Lys/Thr⁶⁴) proinsulin, islet cells infected with adenovirus expressing the mutant proinsulin were pulse labeled (10 min) and chased under basal conditions for 30, 60, or 120 min in presence or absence of the proteosome inhibitor lactacystin (20 μM). (A) Degradation of mutant proinsulin with time of chase. (B) Effect of lactacystin on degradation of mutant proinsulin during a 2-h chase. Data are means of duplicate observations from one of two independent experiments.