TY - JOUR

T1 - Biosynthesis of intestinal microvillar proteins. The effect of swainsonine on post-translational processing of aminopeptidase N

AU - Danielsen, E M

AU - Cowell, G M

AU - Norén, Ove

AU - Sjöström, H

AU - Dorling, P R

N1 - 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

PY - 1983

Y1 - 1983

N2 - 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.

AB - 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.

M3 - Journal article

C2 - 6140919

VL - 216

SP - 325

EP - 331

JO - Biochemical Journal

JF - Biochemical Journal

SN - 0264-6021

IS - 2

ER -