PMID: 6298538Dec 27, 1982

Processing of normal and non-glycosylated forms of toad pro-opiocortin by rat intermediate (pituitary) lobe pro-opiocortin converting enzyme activity

Life Sciences
Y P Loh, H Gainer

Abstract

The influence of glycosylation of a prohormone, pro-opiocortin, on its processing by intermediate (pituitary) lobe converting enzyme activity in vitro was studied. [3H]-arginine-labeled glycosylated and non-glycosylated pro-opiocortins were isolated from untreated, and tunicamycin treated toad neurointermediate lobes, respectively, after pulse-labeling in [3H]-arginine containing incubation media. These labeled precursors were then incubated at 37 degrees C in the presence of pro-opiocortin converting enzyme activity derived from rat intermediate lobe (pituitary) secretory granule lysates. The rates of conversion of the glycosylated and nonglycosylated pro-opiocortins to smaller peptide products, in vitro, were similar. Analysis of the peptide products by immunoprecipitation with ACTH and beta-endorphin antisera, and subsequent electrophoresis on acid-urea gels, indicate a comparable processing in vitro of the two forms of pro-opiocortin substrate. The only difference was that the normally glycosylated peptide products derived from glycosylated pro-opiocortin (i.e., 13K ACTH, 21K ACTH, and the 16K glycopeptide) differed in their gel electrophoretic mobilities from their counterparts derived from nonglycosylated prohormone, in a...Continue Reading

Related Concepts

Metazoa
Metabolic Biotransformation
Cytoplasmic Granules
Endorphins
Glycopeptides
Endopeptidases
Pituitary Stalk
Pituitary Hormones, Anterior
Opiocortin
Protein Precursors

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