Porcine aortic endothelial cell membranes contain a LPAF: CoA-independent transacylase.
Membranes isolated from porcine aortic endothelial cells (PAEC) contain a CoA-independent transacylase enzyme (CoA-IT). CoA-IT, an integral membrane protein, transfers an acyl moiety to added [3H]alkylhydroxyglycerophosphocholine (LPAF) to generate [3H]alkylacylglycerophosphocholine (alkylacyl-GPC). This enzyme exhibits an apparent Km of 0.7 microM and a Vmax of 0.8 nmol/min per mg for the transfer of an acyl group to added [3H]LPAF. The addition of the nonionic detergent Triton X-100 (TX-100) (0.5 mg/ml), the sulfhydryl reagents N-ethylmaleimide (NEM) (200 microM) or thimerosal (200 microM), or pre-incubating the membranes at 95 degrees C for 10 min all decreased LPAF: CoA-IT activity by more than 95%. The inhibitory action of NEM or thimerosal suggests that sulfhydryl group(s) are involved in or are close to the catalytic site of LPAF: CoA-IT.
Jansen
G J
GJ
Department of Medicine and Biochemistry, Boston University School of Medicine, MA.
Pritzker
C R
CR
Deykin
D
D
D000217:Acyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D003065:Coenzyme A / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000201:enzymology*; D007700:Kinetics; D010713:Phosphatidylcholines / Q000378:metabolism*; D013552:Swine
D010713:Phosphatidylcholines; D000217:Acyltransferases; D003065:Coenzyme A