Intracellular trafficking and degradation of unassociated proα2 chains of collagen type I

Abstract

Procollagen I is a trimer consisting of two proα1(I) chains and one proα 2(I) chain. In certain cases of mild osteogenesis imperfecta, abnormal proα1(I) chains are degraded very soon after synthesis. As a consequence, the cells produce excess proα2(I) chains, which cannot form trimers and are not secreted. The objective of this work was to determine the intracellular fate of unassociated proα2(I) chains. Mov13 mouse fibroblasts, which do not synthesize proα1(I) mRNA, but do produce proα2(I) mRNA, were incubated with radioactive amino acids using pulse-chase protocols, and proteins were analyzed by gel electrophoresis, autoradiography, and Western blotting. Mov13 cells produced proα2(I) chain..