Activation of rat liver plasma-membrane diacylglycerol kinase by vasopressin and phenylephrine.
Plasma-membrane fractions were prepared from the livers of rats injected with 0.15 M-NaCl (controls) or vasopressin (1 nmol/kg body wt.). When assayed in the presence of deoxycholate, vasopressin increased the Vmax. of plasma-membrane diacylglycerol kinase 2-4-fold, and the apparent Km of the enzyme for 1,2-dioleoyl-sn-glycerol was doubled. The effect of vasopressin on the Vmax. of plasma-membrane diacylglycerol kinase was twice as great between pH 7 and 8.5 than at pH 6 or 6.5. Vasopressin doubled the activity of diacylglycerol kinase in the plasma-membrane fraction when the enzyme was assayed with phosphatidylserine rather than deoxycholate as stimulator, and when either 1-stearoyl-2-arachidonoyl-sn-glycerol or 1,2-dioleoyl-sn-glycerol was the substrate. In perfused livers vasopressin (10 nM) increased the Vmax. of plasma-membrane diacylglycerol kinase 2-fold, and phenylephrine (3 microM) gave a similar effect. Vasopressin doubled diacylglycerol kinase activity in hepatocytes that had been preincubated for 55 min, but not in cells that had only been preincubated for 15 min.
Rider
M H
MH
Hormone and Metabolic Research Unit, Institute of Cellular and Molecular Pathology (ICP), Brussels, Belgium.
Baquet
A
A
D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D019852:Diacylglycerol Kinase; D004075:Diglycerides / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D066298:In Vitro Techniques; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology*; D010710:Phosphates / Q000378:metabolism; D010770:Phosphotransferases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014667:Vasopressins / Q000494:pharmacology*
D004075:Diglycerides; D010710:Phosphates; D014667:Vasopressins; D010656:Phenylephrine; D010770:Phosphotransferases; D019852:Diacylglycerol Kinase; C013965:diolein