Structure of microvillar enzymes in different phases of their life cycles

H Sjöström; Ove Norén; E M Danielsen; H Skovbjerg

Structure of microvillar enzymes in different phases of their life cycles

H Sjöström, Ove Norén, E M Danielsen, H Skovbjerg

Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › peer review

26 Citationer (Scopus)

Abstract

Udgivelsesdato: 1983-null

Originalsprog	Engelsk
Bogserie	Novartis Foundation Symposium
Vol/bind	95
Sider (fra-til)	50-72
Antal sider	22
ISSN	1528-2511
Status	Udgivet - 1983

Bibliografisk note

Keywords: Aminopeptidases; Animals; Antigens, CD13; Biological Transport; Cell Membrane; DNA Transposable Elements; Glucan 1,4-alpha-Glucosidase; Glycoside Hydrolases; Humans; Intestine, Small; Macromolecular Substances; Microvilli; Protein Biosynthesis; Rabbits; Sucrase-Isomaltase Complex; Swine

Citationsformater

@article{33342200e7be11ddbf70000ea68e967b,

title = "Structure of microvillar enzymes in different phases of their life cycles",

abstract = "Structural changes have been studied during the life cycles of three glycosidases: sucrase-isomaltase (EC 3.2.48-10), lactase-phlorizin hydrolase (EC 3.2.1.23-62), maltase-glucoamylase (EC 3.2.1.20); and three peptidases: aminopeptidase A (EC 3.4.11.7), aminopeptidase N (EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.5). The final forms of the enzymes can be divided into at least two groups: the sucrase-isomaltase type, characterized as dimers, which are asymmetric in their hydrophilic parts, have two types of active site and anchor only on one subunit; and the aminopeptidase N type, characterized as dimers, which are symmetric in their hydrophilic part, have only one type of active site and anchor on both subunits. These enzymes are likely to be synthesized on rough endoplasmic reticulum and simultaneously glycosylated into endoglycosidase H-sensitive forms. They are later reglycosylated to endoglycosidase H-resistant forms, which have relative molecular masses similar to the final forms. Enzymes of the sucrase-isomaltase type seem to be synthesized with a polypeptide-chain length corresponding to the sum of both subunits, whereas enzymes of the aminopeptidase N type seem to be synthesized with a polypeptide-chain length corresponding to the constituent subunits themselves. Not much is known about the catabolism of these enzymes. The enzyme activities and the amounts of enzyme protein decrease at the top of the villi, probably due to release into the lumen. The subunits of aminopeptidase N are cleaved by pancreatic proteases to smaller peptides, and sucrase-isomaltase may lose its sucrase polypeptide, while both enzymes remain bound to the membrane.",

author = "H Sj{\"o}str{\"o}m and Ove Nor{\'e}n and Danielsen, {E M} and H Skovbjerg",

note = "Keywords: Aminopeptidases; Animals; Antigens, CD13; Biological Transport; Cell Membrane; DNA Transposable Elements; Glucan 1,4-alpha-Glucosidase; Glycoside Hydrolases; Humans; Intestine, Small; Macromolecular Substances; Microvilli; Protein Biosynthesis; Rabbits; Sucrase-Isomaltase Complex; Swine",

year = "1983",

language = "English",

volume = "95",

pages = "50--72",

journal = "Novartis Foundation Symposium",

issn = "1528-2511",

publisher = "JohnWiley & Sons Ltd",

}

TY - JOUR

T1 - Structure of microvillar enzymes in different phases of their life cycles

AU - Sjöström, H

AU - Norén, Ove

AU - Danielsen, E M

AU - Skovbjerg, H

N1 - Keywords: Aminopeptidases; Animals; Antigens, CD13; Biological Transport; Cell Membrane; DNA Transposable Elements; Glucan 1,4-alpha-Glucosidase; Glycoside Hydrolases; Humans; Intestine, Small; Macromolecular Substances; Microvilli; Protein Biosynthesis; Rabbits; Sucrase-Isomaltase Complex; Swine

PY - 1983

Y1 - 1983

N2 - Structural changes have been studied during the life cycles of three glycosidases: sucrase-isomaltase (EC 3.2.48-10), lactase-phlorizin hydrolase (EC 3.2.1.23-62), maltase-glucoamylase (EC 3.2.1.20); and three peptidases: aminopeptidase A (EC 3.4.11.7), aminopeptidase N (EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.5). The final forms of the enzymes can be divided into at least two groups: the sucrase-isomaltase type, characterized as dimers, which are asymmetric in their hydrophilic parts, have two types of active site and anchor only on one subunit; and the aminopeptidase N type, characterized as dimers, which are symmetric in their hydrophilic part, have only one type of active site and anchor on both subunits. These enzymes are likely to be synthesized on rough endoplasmic reticulum and simultaneously glycosylated into endoglycosidase H-sensitive forms. They are later reglycosylated to endoglycosidase H-resistant forms, which have relative molecular masses similar to the final forms. Enzymes of the sucrase-isomaltase type seem to be synthesized with a polypeptide-chain length corresponding to the sum of both subunits, whereas enzymes of the aminopeptidase N type seem to be synthesized with a polypeptide-chain length corresponding to the constituent subunits themselves. Not much is known about the catabolism of these enzymes. The enzyme activities and the amounts of enzyme protein decrease at the top of the villi, probably due to release into the lumen. The subunits of aminopeptidase N are cleaved by pancreatic proteases to smaller peptides, and sucrase-isomaltase may lose its sucrase polypeptide, while both enzymes remain bound to the membrane.

AB - Structural changes have been studied during the life cycles of three glycosidases: sucrase-isomaltase (EC 3.2.48-10), lactase-phlorizin hydrolase (EC 3.2.1.23-62), maltase-glucoamylase (EC 3.2.1.20); and three peptidases: aminopeptidase A (EC 3.4.11.7), aminopeptidase N (EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.5). The final forms of the enzymes can be divided into at least two groups: the sucrase-isomaltase type, characterized as dimers, which are asymmetric in their hydrophilic parts, have two types of active site and anchor only on one subunit; and the aminopeptidase N type, characterized as dimers, which are symmetric in their hydrophilic part, have only one type of active site and anchor on both subunits. These enzymes are likely to be synthesized on rough endoplasmic reticulum and simultaneously glycosylated into endoglycosidase H-sensitive forms. They are later reglycosylated to endoglycosidase H-resistant forms, which have relative molecular masses similar to the final forms. Enzymes of the sucrase-isomaltase type seem to be synthesized with a polypeptide-chain length corresponding to the sum of both subunits, whereas enzymes of the aminopeptidase N type seem to be synthesized with a polypeptide-chain length corresponding to the constituent subunits themselves. Not much is known about the catabolism of these enzymes. The enzyme activities and the amounts of enzyme protein decrease at the top of the villi, probably due to release into the lumen. The subunits of aminopeptidase N are cleaved by pancreatic proteases to smaller peptides, and sucrase-isomaltase may lose its sucrase polypeptide, while both enzymes remain bound to the membrane.

M3 - Journal article

C2 - 6133706

VL - 95

SP - 50

EP - 72

JO - Novartis Foundation Symposium

JF - Novartis Foundation Symposium

SN - 1528-2511

ER -