Acetylation of sphingosine by PAF-dependent transacetylase.
Sphingosine induces many protein kinase C-dependent and -independent effects on biological systems. In parallel, C2-ceramide used by investigators as an unnatural, cell permeable analog of long-chain acyl-ceramides, possesses biological activities similar with natural ceramides. We have recently characterized a membrane-associated. CoA-independent transacetylase that can transfer the acetate group from PAF to sphingosine and form C2-ceramide. This enzyme has a strict stereochemical configuration requirement for sphingosine; only the naturally-occurring D-erythro-isomers of sphingosine accepts the acetate from PAF. Also, it has a rigid substrate specificity for sphingolipid-related analogues. Dipalmitoyl-glycerophosphocholine (-GPC) or hexadecylarachidonoyl-GPC can not transfer their long-chain acyl groups directly to sphingosine and sphingosine can not be acetylated by acetyl-CoA:lyso-PAF acetyltransferase. Results obtained from studies on pH optima, subcellular distribution, temperature sensitivities, inhibitors, tissue distributions, and expression of enzyme activities in Xenopus oocytes suggest that PAF:sphingosine transacetylase is similar, but not identical to the PAF:lysophospholipid transacetylase we have previously identified. The transacetylases function to diversify the biological responses of PAF.
Lee
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Medical Sciences Division, Oak Ridge Associated Universities, Tennessee, USA.
D000107:Acetylation; D000123:Acetyltransferases / Q000737:chemistry / Q000378:metabolism*; D018922:HL-60 Cells; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010972:Platelet Activating Factor / Q000502:physiology*; D013110:Sphingosine / Q000378:metabolism*; D013347:Subcellular Fractions / Q000201:enzymology
D010972:Platelet Activating Factor; D000123:Acetyltransferases; C097632:sphingosine CoA-independent transacetylase; D013110:Sphingosine