Evidence for the presence of diacylglycerol kinase in rat brain myelin.
The previous demonstration that incubation of brain slices with [32P]phosphate brings about rapid labeling of phosphatidic acid in myelin suggests that the enzyme involved should be present in this specialized membrane. DAG kinase (ATP:1,2-diacyglycerol 3-phosphotransferase, E.C. 2.7.1.107) is present in rat brain homogenate at a specific activity of 2.5 nmol phosphatidic acid formed/min/mg protein, while highly purified myelin had a much lower specific activity (0.29 nmol/min/mg protein). Nevertheless, the enzyme appears to be intrinsic to this membrane since it can not be removed by washing with a variety of detergents or chelating agents, and it could not be accounted for as contamination by another subcellular fraction. Production of endogenous, membrane-associated, diacylglycerol (DAG) by PLC (phospholipase C) treatment brought about translocation from soluble to particulate fractions, including myelin. Another level of control of activity involves inactivation by phosphorylation; a 10 min incubation of brain homogenate with ATP resulted in a large decrease in DAG kinase activity in soluble, particulate and myelin fractions.
Kahn
D W
DW
Department of Biochemistry and Nutrition, University of North Carolina, Chapel Hill 27599-7250.
Morell
P
P
D000227:Adenine Nucleotides / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002451:Cell Compartmentation / Q000187:drug effects; D019852:Diacylglycerol Kinase; D004075:Diglycerides / Q000378:metabolism; D007700:Kinetics; D009186:Myelin Sheath / Q000201:enzymology*; D010770:Phosphotransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology; D010738:Type C Phospholipases / Q000378:metabolism
D000227:Adenine Nucleotides; D004075:Diglycerides; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; D019852:Diacylglycerol Kinase; D010738:Type C Phospholipases