| Agonist modulated targeting of the EDG 1 receptor to plasmalemmal caveolae . eNOS activation by sphingosine 1 phosphate and the role of caveolin 1 in sphingolipid signal transduction . ^^^ Subcellular fractionation of cell lysates resolved by ultracentrifugation in discontinuous sucrose gradients revealed that approximately 55 % of the EDG 1 protein was recovered in fractions enriched in caveolin 1 , a resident protein of caveolae . ^^^ Co immunoprecipitation experiments showed that EDG 1 could be specifically precipitated by antibodies directed against caveolin 1 and vice versa . ^^^ Overexpression of transfected caveolin 1 cDNA together with EDG 1 and eNOS markedly diminished S1P mediated eNOS activation ; caveolin overexpression also attenuated agonist induced phosphorylation of EDG 1 receptor by > 90 % . ^^^ |