Insulin-like growth factor II receptor is phosphorylated by a tyrosine kinase in adipocyte plasma membranes
Incorporation of /sup 32/P from (gamma-32P)ATP into tyrosine residues of the insulin-like growth factor (IGF)-II receptor was observed in a Triton X-100-insoluble fraction of rat adipocyte plasma membranes. IGF-II receptor phosphorylation proceeded to a stoichiometry of approximately 0.5 mol of phosphate/IGF-II binding site after 10 min of incubation at 4 degrees C. A Km for ATP of 6 microM was calculated for this phosphorylation reaction. Addition of IGF-II caused an approximately 2-fold increase in tyrosine phosphorylation of the IGF-II receptor in this preparation. In contrast, phosphorylation of angiotensin II by the Triton X-100 washed membranes was not stimulated by IGF-II. Incubation of purified receptor immobilized on IGF-II agarose or of receptor-enriched low density microsomal membranes with (gamma-32P)ATP did not result in appreciable incorporation of (/sup 32/P)phosphate into the IGF-II receptor nor into exogenous substrates. These data suggest that the IGF-II receptor is not a tyrosine protein kinase capable of autophosphorylation but that it is a substrate for a tyrosine protein kinase endogenous to the adipocyte plasma membrane. The stimulatory effect of IGF-II on the tyrosine phosphorylation of its receptor may be due to a conformational change which converts the receptor to a better substrate for this tyrosine kinase.
- Research Organization:
- Univ. of Massachusetts Medical Center, Worcester
- OSTI ID:
- 5234380
- Journal Information:
- J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 17; ISSN JBCHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ADIPOSE TISSUE
AMINO ACIDS
ANIMAL TISSUES
ANIMALS
ATP
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHEMICAL REACTIONS
CONNECTIVE TISSUE
DAYS LIVING RADIOISOTOPES
ENZYMES
HYDROXY ACIDS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
MOLECULAR WEIGHT
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHORYLATION
PHOSPHOTRANSFERASES
PROTEINS
RADIOISOTOPES
RATS
RECEPTORS
RODENTS
SUBSTRATES
TISSUES
TRACER TECHNIQUES
TRANSFERASES
TYROSINE
UPTAKE
VERTEBRATES