PMID- 8382701
OWN - NLM
STAT- MEDLINE
DCOM- 19930326
LR  - 20210210
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 268
IP  - 6
DP  - 1993 Feb 25
TI  - Insulin-stimulated phosphatidylinositol 3-kinase. Association with a 185-kDa 
      tyrosine-phosphorylated protein (IRS-1) and localization in a low density 
      membrane vesicle.
PG  - 4391-8
AB  - Insulin stimulates the appearance of anti-tyrosine(P)-immunoprecipitable 
      phosphatidylinositol 3-kinase (PI 3-kinase) activity in adipocytes, predominantly 
      in an intracellular membrane fraction (Kelly, K. L., Ruderman, N. B., and Chen, 
      K. S. (1992) J. Biol. Chem. 267, 3423-3428). Neither the mechanism underlying 
      this activation nor the precise subcellular compartment in which it occurs is 
      known. To address these questions, studies were performed using isolated rat 
      adipocytes and subcellular fractions of these cells. In intact cells, insulin 
      stimulated the rapid appearance of phosphatidylinositol 3,4-bisphosphate and 
      phosphatidylinositol 3,4,5-trisphosphate in 32P-labeled adipocytes without 
      changing the labeling of phosphatidylinositol 3-phosphate, phosphatidylinositol 
      4-phosphate, or phosphatidylinositol 4,5-bisphosphate. This effect was 
      accompanied by the tyrosyl phosphorylation of a 185-kDa protein, tentatively 
      identified as IRS-1, with which PI 3-kinase became associated. The majority of 
      the p85, the regulatory subunit of PI 3-kinase, in untreated adipocytes was 
      present in the cytosol; however, neither the activity of PI 3-kinase nor the 
      total amount of p85 in this fraction was modified in response to insulin. In 
      contrast, insulin increased the association of p85 with IRS-1, the tyrosyl 
      phosphorylation of the IRS-1 associated with p85, and the total activity of PI 
      3-kinase in the plasma membranes and low density membranes. After insulin 
      treatment, similar amounts of p85 were bound to IRS-1 in the low density and 
      plasma membrane fractions; however, tyrosyl-phosphorylated IRS-1 and PI 3-kinase 
      activity were an order of magnitude greater in the low density membranes. The 
      complex of tyrosyl-phosphorylated IRS-1.p85 that formed in response to insulin 
      was localized to a very low density vesicle subpopulation that could be 
      distinguished from vesicles containing the GLUT-4 glucose transporter and the 
      insulin receptor. These data suggest that the activation of PI 3-kinase by 
      insulin in the adipocyte involves the formation of a complex between IRS-1 and PI 
      3-kinase in a very low density membrane fraction that is not enriched in GLUT-4 
      or insulin receptors. They also suggest that PI 3-kinase activation correlates 
      more closely with the extent of tyrosyl phosphorylation of the IRS-1 complexed to 
      PI 3-kinase than it does to the amount of p85 bound to IRS-1.
FAU - Kelly, K L
AU  - Kelly KL
AD  - Boston University Medical Center, Evans Department of Medicine, Massachusetts 
      02118-2393.
FAU - Ruderman, N B
AU  - Ruderman NB
LA  - eng
GR  - DK42621/DK/NIDDK NIH HHS/United States
GR  - T32HL07224/HL/NHLBI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Inositol Phosphates)
RN  - 0 (Insulin)
RN  - 0 (Insulin Receptor Substrate Proteins)
RN  - 0 (Irs1 protein, rat)
RN  - 0 (Phosphoproteins)
RN  - 42HK56048U (Tyrosine)
RN  - EC 2.7.- (Phosphotransferases)
RN  - EC 2.7.1.- (Phosphatidylinositol 3-Kinases)
SB  - IM
MH  - Adipose Tissue/cytology/metabolism
MH  - Amino Acid Sequence
MH  - Animals
MH  - Cell Membrane/enzymology
MH  - Cells, Cultured
MH  - Enzyme Activation
MH  - Inositol Phosphates/biosynthesis
MH  - Insulin/*physiology
MH  - Insulin Receptor Substrate Proteins
MH  - Male
MH  - Molecular Sequence Data
MH  - Phosphatidylinositol 3-Kinases
MH  - Phosphoproteins/*metabolism
MH  - Phosphotransferases/*metabolism
MH  - Rats
MH  - Rats, Sprague-Dawley
MH  - Tyrosine/*metabolism
EDAT- 1993/02/25 00:00
MHDA- 1993/02/25 00:01
CRDT- 1993/02/25 00:00
PHST- 1993/02/25 00:00 [pubmed]
PHST- 1993/02/25 00:01 [medline]
PHST- 1993/02/25 00:00 [entrez]
AID - S0021-9258(18)53622-X [pii]
PST - ppublish
SO  - J Biol Chem. 1993 Feb 25;268(6):4391-8.