O-linked oligosaccharides on insulin receptor
- National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD (USA)
The insulin receptor, an integral membrane glycoprotein, is synthesized as a single-chain precursor that is cleaved to produce two mature subunits, both of which contain N-linked oligosaccharide chains and covalently linked fatty acids. We report that the beta-subunit also contains O-linked oligosaccharides. The proreceptor, alpha-subunit, and beta-subunit were labeled with (3H)mannose and (3H)galactose in the presence or absence of an inhibitor of O-linked glycosylation. Tryptic peptides from each component were separated by reverse-phase high-performance liquid chromatography. N- and O-linked oligosaccharide chains were identified on these peptides by specific enzymatic digestions. The proreceptor and alpha-subunit contained only N-linked oligosaccharides, whereas the beta-subunit contained both N- and O-linked oligosaccharides. The O-linked oligosaccharide chains were attached to a single tryptic fraction of the beta-subunit, which also contained N-linked chains. This fraction was further localized to the NH2-terminal tryptic peptide of the beta-subunit by specific immunoprecipitation with an anti-peptide antibody with specificity for this region. Binding of insulin and autophosphorylation of the beta-subunit were not dependent on O-linked glycosylation, because cells grown in the presence of the inhibitor exhibited a normal dose response to insulin. Therefore, the insulin receptor contains O-linked oligosaccharides on the NH2-terminal tryptic peptide of the beta-subunit, and these O-linked oligosaccharides are not necessary to the binding or autophosphorylation function of the receptor.
- OSTI ID:
- 6062326
- Journal Information:
- Diabetes; (USA), Vol. 40:2; ISSN 0012-1797
- Country of Publication:
- United States
- Language:
- English
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INSULIN
RECEPTORS
OLIGOSACCHARIDES
BIOLOGICAL LOCALIZATION
AMINO ACID SEQUENCE
BIOCHEMICAL REACTION KINETICS
FIBROBLASTS
GALACTOSE
LIQUID COLUMN CHROMATOGRAPHY
LYMPHOCYTES
MANNOSE
PHOSPHORYLATION
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ALDEHYDES
ANIMAL CELLS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARBOHYDRATES
CHEMICAL REACTIONS
CHROMATOGRAPHY
CONNECTIVE TISSUE CELLS
HEXOSES
HORMONES
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
LEUKOCYTES
MATERIALS
MEMBRANE PROTEINS
MOLECULAR STRUCTURE
MONOSACCHARIDES
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PROTEINS
REACTION KINETICS
SACCHARIDES
SEPARATION PROCESSES
SOMATIC CELLS
550201* - Biochemistry- Tracer Techniques