Biosynthesis of intestinal microvillar proteins. Dimerization of aminopeptidase N and lactase-phlorizin hydrolase

Journal Article · Tue Jan 09 04:00:00 EST 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00453a042· OSTI ID:6897780

Danielsen, E M ^[1]

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1. Univ. of Cophenhagen (Denmark)

The pig intestinal brush border enzymes aminopeptidase and lactase-phlorizin hydrolase are present in the microvilla membrane as homodimers. Dimethyl adipimidate was used to cross-link the two ({sup 35}S)methionine-labeled brush border enzymes from cultured mucosal explants. For aminopeptidase N, dimerization did not begin until 5-10 min after synthesis, and maximal dimerization by cross-linking of the transient form of the enzyme required 1 h, whereas the mature form of aminopeptidase N cross-linked with unchanged efficiency from 45 min to 3 h of labeling. Formation of dimers of this enzyme therefore occurs prior to the Golgi-associated processing, and the slow rate of dimerization may be the rate-limiting step in the transport from the endoplasmic reticulum to the Golgi complex. For lactase-phlorizin hydrolase, the posttranslational processing includes a proteolytic cleavage of its high molecular weight precursor. Since only the mature form and not the precursor of this enzyme could be cross-linked, formation of tightly associated dimers only takes place after transport out of the endoplasmic reticulum. Dimerization of the two brush border enzymes therefore seems to occur in different organelles of the enterocyte.

• OSTI ID: 6897780
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:1; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
AMINOPEPTIDASES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOSYNTHESIS
BODY
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
CROSS-LINKING
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
DIMERIZATION
DOMESTIC ANIMALS
DRUGS
ELECTROPHORESIS
ENZYMES
EVEN-ODD NUCLEI
GASTROINTESTINAL TRACT
GLYCOPROTEINS
GLYCOSYL HYDROLASES
HYDROLASES
INTESTINES
ISOTOPES
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAMMALS
MEMBRANES
METHIONINE
MUCOUS MEMBRANES
NUCLEI
O-GLYCOSYL HYDROLASES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
PEPTIDE HYDROLASES
POLYMERIZATION
PROTEINS
RADIOISOTOPES
SULFUR 35
SULFUR ISOTOPES
SWINE
SYNTHESIS
VERTEBRATES