Synthesis of type I procollagen: formation of interchain disulfide bonds before complete hydroxylation of the protein.
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Matrix-free cells from chick embryo tendons were incubated for 2 h with [14C]proline or [14C]lysine to achieve steady-state labeling of intracellular proteins. Cell homogenates were then examined by velocity sedimentation under conditions in which nonhelical proγ chains of procollagen sediment more rapidly than other procollagen polypeptides. With these procedures it was shown that the cells contained some proγ chains which were either not triple helical or were in an unstable triple-helical conformation. These proγ chains were shown to contain less hydroxyproline than the triple-helical procollagen secreted by the cells. Their content of glycosylated hydroxylysine, however, was greater than that of the procollagen secreted by the cells. The results indicate that some of the procollagen synthesized by chick embryo tendon is assembled by the sequence in which disulfide bonding precedes complete hydroxylation. The proγ chains synthesized by this alternate route may reflect errors in protein assembly or may serve as a source of microheterogeneity in collagen. © 1981.
author list (cited authors)
Uitto, V. J., Uitto, J., & Prockop, D. J
complete list of authors
Uitto, VJ||Uitto, J||Prockop, DJ