Hydroxylation of proline and the intracellular accumulation of a polypeptide precursor of collagen

Autoradiographs of embryonic cartilage indicated that labeled protein accumnulated intracellularly when the tissue was incubated with tritiated proline, and when the hydroxylation of proline was inhibited by anaerobic conditions or by a chelator for ferrous iron. The labeled protein apparently corresponds to protocollagen. the polypeptide precursor of collagen which serves as a substrate for the enzymatic synthesis of hydroxyproline.