Ref ID : 4395
Young-Gyu Ko and Jr. Guy A. Thompson; Immobilization Antigens from Tetrahymena thermophila Are Glycosyl-Phosphatidylinositol-Linked Proteins. J.Protozool. 39(6):719-723, 1992
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We have studied four strains of Tetrahymena thermophila, each of which expresses a different allele of the SerH gene and produces a distinctive surface protein of the immobilization antigen (i-antigen) class. Following exposure of the strains to [3H]ethanolamine or [3H]myristic acid, a protein corresponding in molecular mass to the characteristic i-antigen for that strain became highly labeled, as determined by mobility is sodium dodecylsulfate-polyacrylamide electrophoresis gels. Furthermore, antibodies raised to the i-antigens of the T. thermophila strains selectively immunoprecipitated redioactive proteins having molecular mass identical to that of the i-antigens characteristics for that particular strain. The lipid moieties labeled by [3H]myristate were not susceptible to hydrolysis by exogenous phosphatidylinositol-specific phospholipase C from bacteria. However, when protein extraction was carried out in the absence of phospholipase C inhibitors, radioactive fatty acids derived from [3H]myristate were rapidly cleaved from the putative i-antigens. On the basis of available data, it was concluded that T. thermophila i-antigens contain covalently-linked glycosyl-phosphatidylinositol anchors.