Evidence for a role of phosphatidylinositol 3-kinase in the regulation of glucose transport in Xenopus oocytes.
We have used two experimental approaches to examine the possible role of phosphatidylinositol 3-kinase (PI 3-kinase) in the regulation of glucose transport in oocytes isolated from Xenopus laevis. Incubation of oocytes with the PI 3-kinase inhibitor wortmannin inhibited insulin-like growth factor-1-stimulated deoxyglucose uptake. Half-maximal inhibition was observed at concentrations approximately 20 nM. Conversely, we also examined the effects of microinjection of synthetic peptides designed to interact with Src homology 2 domains of the regulatory subunit of PI 3-kinase on deoxyglucose transport in oocytes. We show that a bifunctional synthetic peptide containing two YMXM consensus sequences for binding to SH2 domains stimulated both PI 3-kinase activity and deoxyglucose transport when both tyrosine residues were phosphorylated. However, non-phosphorylated or bisphosphonotyrosine peptides with the identical amino acid sequence failed to stimulate transport or PI 3-kinase activity. Taken together, these data argue strongly for a role for PI 3-kinase in the regulation of glucose transport in oocytes.
Gould
G W
GW
Department of Biochemistry, University of Glasgow, Scotland, United Kingdom.
Jess
T J
TJ
Andrews
G C
GC
Herbst
J J
JJ
Plevin
R J
RJ
Gibbs
E M
EM
D000595:Amino Acid Sequence; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003847:Deoxyglucose / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005947:Glucose / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D008845:Microinjections; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000494:pharmacology; D009865:Oocytes / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011485:Protein Binding; D000077191:Wortmannin; D014982:Xenopus laevis / Q000378:metabolism*
D000730:Androstadienes; D009842:Oligopeptides; D007334:Insulin-Like Growth Factor I; D003847:Deoxyglucose; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D005947:Glucose; D000077191:Wortmannin