Structural differences between liver- and muscle-derived insulin receptors in rats
The structure of insulin receptors, solubilized from rat skeletal muscle and liver, was studied. The ..cap alpha.. subunit was identified by specific cross-linking to A14 /sup 125/I-insulin with disuccinimidyl suberate. Muscle- and liver-derived ..cap alpha.. subunits migrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with a M/sub r/ of 131,000 and 135,000, respectively. There was no significant difference in insulin binding affinity. Treatment of cross-linked, immunoprecipitated receptors with either neuraminidase or endoglycosidase H decreased the M/sub r/ of muscle- and liver-derived ..cap alpha.. subunits but did not affect the difference in M/sub r/. Autophosphorylated ..beta.. subunits migrated with a M/sub r/ of 98,000 for muscle and 101,000 for liver. After partial V8 digestion of autophosphorylated, immunoprecipitated receptors the major phosphopeptide fragment migrated on SDS-PAGE at M/sub r/ 57,000 from muscle and 60,000 from liver. Glycosidase digestion of autophosphorylated receptors suggested that M/sub r/ heterogeneity was due in part to differences in the sialic acid content of ..beta.. subunits. Muscle and liver are the major target organs of insulin; the apparent heterogeneity of insulin receptor structure may be relevant to tissue-specific differences in insulin action.
- Research Organization:
- Medical Univ. of South Carolina, Charleston
- OSTI ID:
- 7090901
- Journal Information:
- J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 261:31; ISSN JBCHA
- Country of Publication:
- United States
- Language:
- English
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550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
ANIMALS
ANTIBODIES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
GLANDS
HORMONES
INSULIN
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
LIVER
MAMMALS
MEMBRANE PROTEINS
MOLECULAR STRUCTURE
MOLECULAR WEIGHT
MUSCLES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORYLATION
PROTEINS
RADIOISOTOPES
RADIORECEPTOR ASSAY
RATS
RECEPTORS
RODENTS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES