FIG. 4.

Digestion of P₄₁ with trypsin. Purified P₄₁ was incubated with trypsin as described in Materials and Methods, and at various times aliquots (10 μg of protein) were subjected to SDS-PAGE (15% gel). The numbers below the lanes give the percentages of the initial activity of the enzyme assayed as described in Materials and Methods; the value for undigested P₄₁ was set at 100%. The GPR samples in lanes 1 to 6 run were digested for 0, 2, 5, 15, 30, and 60 min, respectively. The two bands in lane 4 were taken for analysis of molecular weight and N-terminal protein sequence. Molecular weight markers run in parallel (not shown) indicated that the latter two bands ran at 29 and 27 kDa.