In addition, immunocytochemical localization showed that a small proportion of SRIF molecules accumulated in secretory vesicles. About 22% of SRIF-related products were proteolytically processed to mature SRIF, of which 38.7% were stored intracellularly with a half-life of - 2 h. When pulse-labeled cells were chased for up to 2 h, intracellular propeptides disappeared with a half-life of approximately 25 min, showing that -68% of initially synthesized propeptides were secreted constitutively. Processing and secretion of metabolically labeled hybrid propeptides to mature SRIF peptides were assessed by HPLC. This difference may be due to the differences in ER translocation between yeast and mammalian cells, i.e., posttranslational versus cotranslational translocation. A hybrid construct with a mutated signal peptide underwent similar ER translocation, whereas such a mutation resulted in defective translocation in yeast (Cheong et al., 1997).

These data indicate that prepro region of yeast alpha-factor functions in sorting molecules to secretory pathway in mammalian cells.

We report that nascent hybrid polypeptides were efficiently targeted to ER, where cleavage of signal peptides and core glycosylation occurred, and were localized mainly in Golgi. Chimeric genes coding for prepro region of yeast alpha-factor and anglerfish SRIF were expressed in rat GH3 cells to determine whether yeast signals could regulate hormone processing in mammalian cells.

Prepros 6 no funciona