BIOSYNTHESIS OF ABNORMAL COLLAGENS WITH AMINO ACID ANALOGUES .2. INABILITY OF CARTILAGE CELLS TO EXTRUDE COLLAGEN POLYPEPTIDES CONTAINING L-AZETIDINE-2-CARBOXYLIC ACID OR CIS-4-FLUORO-L-PROLINE

Autoradiographic studies demonstrated that the abnormal collagen polypeptides synthesized in the presence of l-azetidine-2-carboxylic acid or cis-4-fluoro-l-proline are retained intracellularly, and they are not extruded into the extracellular matrix. The proline analogues did not in themselves prevent the extrusion of previously accumulated normal protocollagen after the protocollagen was hydroxylated to collagen, and the results indicated that the failure to extrude the abnormal collagens is directly related to the incorporation of the proline analogues into the polypeptide chains. In exploring the reasons why the collagens containing either analogue are not extruded, it was found that the abnormal collagens not only have a decreased content of hydroxyproline, but also have a decreased content of hydroxylysine and glycosylated hydroxylysine. © 1969.