[14C]leucine chloromethylketone interaction with sarcoma 37 cell plasma membrane components

Leucine chloromethylketone labeling of viable S37 cells was preferential for the plasma membrane fraction. The pattern of radiolabeling of the plasma membrane proteins was time dependent. After 5 min the radiolabel was localized with glutamyl transpeptidase, and subsequently with other physiologically active proteins as a function of time after incubation. Labeling of proteins was temperature dependent and incubation of viable S37 cells with the radiolabeled substrate at 0 degrees C yielded little or no radioactivity localized in the plasma membrane. The molecular weight of one radiolabeled substrate--membrane protein complex was estimated on sodium dodecyl sulfate polyacrylamide gel electrophoresis to be between 100,000-200,000.