JBC, Vol. 252, Issue 3, 955-962, Feb, 1977
Impaired conversion of procollagen to collagen by fibroblasts and bone treated with tunicamycin, an inhibitor of protein glycosylation
D. Duksin and P. Bornstein
Tunicamycin, an inhibitor of lipid carrier-dependent protein glycosylation,
was used in studies of procollagen synthesis, secretion, and proteolytic
modification by chick cranial bones in organ culture and by chick tendon
fibroblasts in tissue culture. Tunicamycin inhibited the incorporation of
D-[2-3H]mannose into procollagen by greater than 90% whereas general
protein synthesis and collagen synthesis were decreased by only 10 to 20%.
The procollagen synthesized in the presence of tunicamycin was secreted
normally and its immunological characteristics, as detected by an antiserum
to the intact protein, were unchanged. However, tunicamycin caused an
accumulation of biosynthetic intermediates containing disulfide-bonded
COOH-terminal extensions in both cell and bone culture. Cleavage of
NH2-terminal extensions was not detectably impaired. These findings provide
additional support for the involvement of more than one enzyme in the
limited proteolytic conversion of procollagen to collagen.