Coated vesicles purified from chick tendon fibroblasts contain newly synthesized type I procollagen

Coated vesicles were purified from embryonic chick tendon fibroblasts pulsed with [3H]proline. They were morphologically and biochemically similar to coated vesicles purified from other sources. Furthermore, they contained newly synthesized Type I procollagen which was protected from bacterial collagenase digestion unless detergent was present. The procollagen remained associated with coated vesicles during immune precipitation and agarose gel electrophoresis. Data from pulse-chase experiments demonstrated that the specific activity of the coated vesicle preparations was approx. 5-fold higher at the 10 min chase point than at either the 0 or 40 min chase points. These data are consistent with the hypothesis that coated vesicles are intermediates in the intracellular transport of newly synthesized Type I procollagen in chick tendon fibroblasts.