Synthesis and secretion of procathepsin B and cystatin C by human bronchial epithelial cells in vitro: modulation of cathepsin B activity by neutrophil elastase
Procathepsin B and cystatin C are found in human lung secretions. We investigated the capacity of human bronchial epithelial cells to synthesize and secrete these proteins. Immunoprecipitation of [35S]methionine-labeled proteins from cultured bronchial epithelial cell lysates, followed by denaturing gel electrophoresis and autoradiography, showed the presence of newly synthesized procathepsin B of
