TY - JOUR

T1 - Biosynthesis of intestinal microvillar proteins. Pulse-chase labelling studies on maltase-glucoamylase, aminopeptidase A and dipeptidyl peptidase IV

AU - Danielsen, E M

AU - Sjöström, H

AU - Norén, Ove

N1 - Keywords: Acetylglucosaminidase; Aminopeptidases; Animals; Dipeptidyl Peptidases; Electrophoresis, Polyacrylamide Gel; Endopeptidases; Glucan 1,4-alpha-Glucosidase; Glucosidases; Glutamyl Aminopeptidase; Intestine, Small; Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; Membrane Proteins; Microvilli; Organ Culture Techniques; Swine

PY - 1983

Y1 - 1983

N2 - The biogenesis of three intestinal microvillar enzymes, maltase-glucoamylase (EC 3.2.1.20), aminopeptidase A (aspartate aminopeptidase, EC 3.4.11.7) and dipeptidyl peptidase IV (EC 3.4.14.5), was studied by pulse-chase labelling of pig small-intestinal explants kept in organ culture. The earliest detectable forms of the enzymes were polypeptides of Mr 225000, 140000 and 115000 respectively. These were found to represent the enzymes in a 'high-mannose' state of glycosylation, as judged by their susceptibility to treatment with endo-beta-N-acetylglucosaminidase H (EC 3.2.1.96). After about 40-60 min of chase, maltase-glucoamylase, aminopeptidase A and dipeptidyl peptidase IV were further modified to yield the mature polypeptides of Mr 245000, 170000 and 137000 respectively, which were expressed at the microvillar membrane after 60-90 min of chase. The fact that the enzymes before reaching the microvillar membrane were found in a Ca2+-precipitated membrane fraction (intracellular and basolateral membranes), but not in soluble form, indicates that during biogenesis maltase-glucoamylase, aminopeptidase A and dipeptidyl peptidase IV are transported and assembled in a membrane-bound state.

AB - The biogenesis of three intestinal microvillar enzymes, maltase-glucoamylase (EC 3.2.1.20), aminopeptidase A (aspartate aminopeptidase, EC 3.4.11.7) and dipeptidyl peptidase IV (EC 3.4.14.5), was studied by pulse-chase labelling of pig small-intestinal explants kept in organ culture. The earliest detectable forms of the enzymes were polypeptides of Mr 225000, 140000 and 115000 respectively. These were found to represent the enzymes in a 'high-mannose' state of glycosylation, as judged by their susceptibility to treatment with endo-beta-N-acetylglucosaminidase H (EC 3.2.1.96). After about 40-60 min of chase, maltase-glucoamylase, aminopeptidase A and dipeptidyl peptidase IV were further modified to yield the mature polypeptides of Mr 245000, 170000 and 137000 respectively, which were expressed at the microvillar membrane after 60-90 min of chase. The fact that the enzymes before reaching the microvillar membrane were found in a Ca2+-precipitated membrane fraction (intracellular and basolateral membranes), but not in soluble form, indicates that during biogenesis maltase-glucoamylase, aminopeptidase A and dipeptidyl peptidase IV are transported and assembled in a membrane-bound state.

M3 - Journal article

C2 - 6407473

VL - 210

SP - 389

EP - 393

JO - Biochemical Journal

JF - Biochemical Journal

SN - 0264-6021

IS - 2

ER -