Kinetics of processing of type I and type III procollagens in fibroblast cultures.

Abstract

The rates of conversion of types I and III procollagens to their respective collagens were compared in 7 fibroblast culture systems [mouse lines Balb/3T3, Swiss 3T3 and Swiss 3T6; 3 normal skin fibroblast strains and a human fetal skin fibroblast strain] of murine or human origin. During 24 h of radioactive labeling or after shorter pulses followed by chases of 20-48 h, no evidence was obtained for conversion of radiolabeled type III procollagen to insoluble collagen. In the same cultures and under the same conditions, native collagen was generated from radiolabeled type I procollagen. There was no evidence for proteolytic degradation of type III procollagen during the chase experiments. The results are ascribed to a lack of availability of the enzymes required for processing of type III procollagen.