Procollagen synthesized by newborn rat skin in culture

Newborn rat skin explants in culture have been found to synthesize and secrete into the medium a considerable amount of collagen precursors (procollagens). Gel-electrophoresis analysis of the material extracted from the medium indicates that it is constituted mainly by procollagen Type I with a small percentage of procollagen Type III. Antibodies have been raised to the extracted procollagen and, although no attempt has been made to render these antibodies specific to one procollagen type by appropriate immunoadsorption, the immunofluorescence patterns that have been obtained are in good agreement with those reported on procollagen Type I by other groups. When unfixed cultured fibroblasts are examined by indirect immunofluorescence in the presence of the antiprocollagen antibody, a fluorescent network of interwoven fibres on the cell surface is observed which is similar to the network formed by fibronectin (LETS) on the fibroblasts' cell membranes.