Figure 2.

Proinsulin mRNA levels and the time course of induction of proinsulin synthesis by glucose (adapted from Ref. 17). Rat pancreatic islets were incubated at 37 ℃ in the presence of 2.8 mM (filled squares) or 25 mM (filled circles) glucose and [³H]leucine. A. [³H]Leucine-labeled products in the islets were analyzed by SDS-polyacrylamide gel electrophoresis and the amount of de novo synthesized proinsulin was determined by summing ³H-radioactivity of the gel slices corresponding to the proinsulin peak. B. Aliquots of the nucleic acids from the incubated islets were used for the quantification of proinsulin mRNA by hybridization with proinsulin cDNA.