Acylation in vivo of the contact site A glycoprotein and of other membrane proteins in Dictyostelium discoideum

AbstractCells of Dictyostelium discoideum were incubated during the preaggregation phase with [3H] palmitic acid, and association of the fatty acid label with proteins was investigated by SDS-polyacrylamide gel electrophoresis and fluorography. Three proteins with apparent molecular masses of 44, 80 and 130kDa were preferentially labeled. The 80-kDa protein proved to be identical with an integral membrane glycoprotein called contact site A. The protein retained the 3H label after chloroform-methanol extraction and boiling in SDS-containing buffer, but not after mild hydroxylamine treatment, indicating an ester bond. After treatment of the protein with KOH the 3H label was recovered in free palmitic acid, as demonstrated by gas-liquid chromatography of the methyl ester