Glucosidase II, a protein of the endoplasmic reticulum with high mannose oligosaccharide chains and a rapid turnover
Glucosidase II is regarded as a resident protein of the endoplasmatic reticulum. The enzyme removes alpha-1-3-linked glucose from high mannose oligosaccharides N-linked to asparagine residues of glycoproteins. Monospecific antibodies raised against the pig kidney enzyme are used to study the metabolism of the enzyme in a rat hepatoma cell line. These antiglucosidase II antibodies specifically immune precipitate glucosidase II as a 100,000-Da species from (/sup 35/S)methionine-labeled cells. In addition, protein blotting and immune staining of cell extracts from both rat liver and human and rat hepatoma cell lines show identity in apparent Mr (100,000). Glucosidase II synthesized in the presence of tunicamycin is approximately 94,000 Da, indicating the presence of one or more N-linked oligosaccharide chains. Cell-free protein synthesis of rat hepatoma total RNA demonstrates that glucosidase II is synthesized as a slightly higher molecular weight species as compared to the polypeptide synthesized in whole cells in the presence of tunicamycin, indicating that the enzyme has a cleavable signal sequence. Using a pulse-chase protocol, the apparent molecular weight does not change upon longer chase periods. In addition, the 100,000-Da protein remains sensitive to endo-beta-N-acetylglucosaminidase H regardless of prolonged chase periods. The cells incorporate (/sup 3/H)mannose into the enzyme; after release with endo-beta-N-acetylglucosaminidase H, most of the radioactivity comigrates with Glc1-Man9-GlcNAc on a gel filtration column.
- Research Organization:
- Univ. of Utrecht, Medical School, The Netherlands
- OSTI ID:
- 6863440
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 8
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GLUCOSIDASE
BIOSYNTHESIS
MOLECULAR BIOLOGY
BIOCHEMICAL REACTION KINETICS
ENDOPLASMIC RETICULUM
GLYCOSYL HYDROLASES
HEPATOMAS
MANNOSE
METHIONINE
MOLECULAR WEIGHT
OLIGOSACCHARIDES
RATS
RNA
SULFUR 35
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ALDEHYDES
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOHYDRATES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
DISEASES
DRUGS
ENZYMES
EVEN-ODD NUCLEI
HEXOSES
HYDROLASES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLED COMPOUNDS
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAMMALS
MONOSACCHARIDES
NEOPLASMS
NUCLEI
NUCLEIC ACIDS
O-GLYCOSYL HYDROLASES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANOIDS
RADIOISOTOPES
REACTION KINETICS
RODENTS
SACCHARIDES
SULFUR ISOTOPES
SYNTHESIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques