Activation of magnesium-dependent, neutral sphingomyelinase by phosphatidylserine.
The plasma membrane isolated from rat ascites hepatoma, AH 7974 cells was treated with 1% Triton X-100, which resulted in a more than 80% reduction in the phospholipid content of the plasma membrane. The delipidized plasma membrane showed only 18% of the activity of the magnesium-dependent, neutral sphingomyelinase in the untreated plasma membrane. On the addition of acidic phospholipids, especially phosphatidylserine, however, the enzyme activity in the delipidized membrane was markedly restored up to 77% of that in the untreated membrane. It was suggested that, considering the phospholipid composition of the AH 7974 plasma membrane (Koizumi, K. et al. (1977) Cell Struct. Func. 2, 145-153), phosphatidylserine may be a natural activator of neutral sphingomyelinase.
D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D008114:Liver Neoplasms, Experimental / Q000201:enzymology; D008274:Magnesium / Q000494:pharmacology*; D010718:Phosphatidylserines / Q000494:pharmacology*; D010743:Phospholipids / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D051381:Rats; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism*
D010718:Phosphatidylserines; D010743:Phospholipids; D010727:Phosphoric Diester Hydrolases; D013108:Sphingomyelin Phosphodiesterase; D008274:Magnesium