Insulin induces activation of kinase FA in membranes and thereby promotes activation of ATP.Mg-dependent phosphatase in adipocytes.
Exposure of rat adipocytes to physiological concentrations of insulin resulted in a time- and concentration-dependent activation-translocation of kinase FA (an activating factor of ATP.Mg-dependent protein phosphatase) in plasma membranes and the subsequent activation of ATP.Mg-dependent protein phosphatase in the cytosol. The insulin-induced activation of membrane-associated kinase FA and cytosolic ATP.Mg-dependent protein phosphatase occurred very rapidly, reaching the maximal activity levels within 3 min. Moreover, the insulin effect is transient; the insulin-stimulated FA activity in membranes and ATP.Mg-dependent phosphatase activity in the cytosol returned to control levels within 30 min. It is concluded that insulin may induce the activation of kinase FA in membranes and thereby promotes the activation of ATP.Mg-dependent multifunctional protein phosphatase in the cytosol of rat adipocytes in order to mediate some of its intracellular effects through the dephosphorylation reactions. The release of factor FA from plasma membranes may represent one of the transmembrane signalling mechanisms for insulin actions.
Yang
S D
SD
Institute of Life Science, National Tsing Hua University, Taiwan, Republic of China.
Ho
L T
LT
Fung
T J
TJ
Yu
J S
JS
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000273:Adipose Tissue / Q000201:enzymology*; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002462:Cell Membrane / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D017830:Octoxynol; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D007328:Insulin; D011092:Polyethylene Glycols; D000255:Adenosine Triphosphate; D017830:Octoxynol; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D008274:Magnesium