Cell-free synthesis of procollagen: L-929 fibroblasts as a cellular model for dermatosparaxis.

A cell-free system that actively synthesizes collagen was prepared from L-929 fibroblasts. Chromatographic and electrophoretic techniques were used to demonstrate that the only collagenous products are pro alpha(1) and pro alpha(2) chains. The collagen synthesized by the cell-free system was also compared to the collagen extracted from the cells. The cellular collagen was composed of aggregates of pro-alpha chains, while no alpha chains were found. Procollagen peptidase activity could not be detected in the cells, and the activity present in the medium was low, comparable to that in dermatosparaxic cell cultures. These properties indicate that L-929 cells may be a model system for dermatosparaxis.