Biosynthesis of intestinal microvillar proteins. The effect of swainsonine on post-translational processing of aminopeptidase N
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The post-translational processing of pig small-intestinal aminopeptidase N (EC 3.4.11.2) was studied in organ-cultured mucosal explants. Exposure of the explants to swainsonine, an inhibitor of Golgi mannosidase II, resulted in the formation of a Mr-160000 polypeptide, still sensitive to endo-beta-N-acetylglucosaminidase H. Swainsonine caused only a moderate inhibition of transport of the enzyme through the Golgi complex and the subsequent expression in the microvillar membrane. This may imply that the trimming of the high-mannose core and complex glycosylation of N-linked oligosaccharides is not essential for the transport of aminopeptidase N to its final destination. A different type of processing was observed to take place in the presence of swainsonine, resulting in a considerable increase in apparent Mr (from 140000 to 160000). This processing could not be ascribed to N-linked glycosylation, since treatment of the Mr-160000 polypeptide with endo-beta-N-acetylglucosaminidase H only decreased its apparent Mr by 15000. The susceptibility of the mature Mr-166000 polypeptide, but not the Mr-140000 polypeptide, to mild alkaline hydrolysis suggests that aminopeptidase N becomes glycosylated with O-linked oligosaccharides during its passage through the Golgi complex. Aminopeptidase N was not labelled by [3H]palmitic acid, indicating that the processing of the enzyme does not include acylation.
Original language | English |
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Journal | Biochemical Journal |
Volume | 216 |
Issue number | 2 |
Pages (from-to) | 325-31 |
Number of pages | 6 |
ISSN | 0264-6021 |
Publication status | Published - 1983 |
Bibliographical note
Keywords: Acetylglucosaminidase; Alkaloids; Aminopeptidases; Animals; Antigens, CD13; Biological Transport; Electrophoresis, Polyacrylamide Gel; Hydrolysis; Intestinal Mucosa; Lectins; Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; Microvilli; Organ Culture Techniques; Plant Lectins; Protein Processing, Post-Translational; Swainsonine; Swine
ID: 9881379