Insulin-induced decrease in protein phosphorylation in rat adipocytes not explained by decreased A-kinase activity
In isolated rat adipocytes, insulin inhibits lipolysis to a greater extent than would be predicted by the decrease in (-/+)cAMP activity ratio of cAMP-dependent protein kinase (A-kinase), from which it was speculated that insulin promotes the dephosphorylation of hormone-sensitive lipase. They have examined the phosphorylation state of cellular proteins under conditions of varying A-kinase activities in the presence and absence of insulin. Protein phosphorylation was determined by SDS-PAGE electrophoresis of extracts from /sup 32/P-loaded cells; glycerol and A-kinase activity ratios were measured in the cytosolic extracts from control, non-radioactive cells. Increased protein phosphorylation in general occurred over the same range of A-kinase activity ratios, 0.1-0.3, associated with increased glycerol release. The insulin-induced decrease in lipolysis was associated with a decrease in the /sup 32/P content of several proteins, an effect not explained by the modest reduction in A-kinase activity by insulin. This effect of insulin on protein phosphorylation was lost as the A-kinase activity ratios exceeded 0.5. The results suggest that insulin promotes the dephosphorylation of those adipocyte proteins which are subject to phosphorylation by A-kinase.
- Research Organization:
- National Institute of Health, Bethesda, MD
- OSTI ID:
- 6079302
- Report Number(s):
- CONF-870644-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 46:6; ISSN FEPRA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ALCOHOLS
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
ELECTROPHORESIS
ENZYME ACTIVITY
ENZYMES
FAT CELLS
GLYCEROL
HORMONES
HYDROXY COMPOUNDS
INHIBITION
INSULIN
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MAMMALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHORYLATION
PHOSPHOTRANSFERASES
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RODENTS
SOMATIC CELLS
TRACER TECHNIQUES
TRANSFERASES
VERTEBRATES