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Retention of nonhelical procollagen containing cis-hydroxyproline in rough endoplasmic reticulum

Fibroblasts freshly isolated from embryonic tendons were incubated with a proline analog, cis-4-hydroxy-L-proline, which is incorporated into protein and which leads to the intracellular accumulation of nonhelical procollagen. Evidence is presented here that the nonhelical procollagen containing the analog is retained within the rough endoplasmic reticulum and does not pass to the smooth endoplasmic reticulum or Golgi vacuoles at a normal rate.