In vitro synthesis and glycosylation of androgen‐dependent secretory proteins of rat dorsal prostate and coagulating gland

The two major androgen‐dependent secretory proteins of rat dorsal prostate and coagulating gland, DP I and DP II, were compared by in vitro translation of total poly(A)RNA and by pulse‐chase techniques by means of [ 35 S]methionine and tissue minces of coagulating gland. DP I is a major in vitro translation product of isolated poly(A)RNA, whereas DP II is undetectable in a mouse embryo fibroblast cell‐free system where glycosylation does not occur. DP I is synthesized within 20 min in minces of coagulating gland incubated in the presence of [ 35 S]methionine and is secreted in 40 min. DP II is detectable in the medium only after 8 hr of labeling. Inhibition of asparagine‐linked protein glycosylation with tunicamycin (10 μg/ml) blocked the synthesis and secretion of DP II with an apparent increase in DP I secretion. Inhibition of DP II synthesis by monensin implicates the Golgi in the processing of DP II oligosaccharides. The data are consistent with the proposal that DP I enters a pathway of rapid secretion that is enhanced by the absence of core glycosylation, whereas DP II follows a slow pathway through the Golgi that involves extensive glycosylation.