CLONING OF A CDNA-ENCODING A 2ND PHOSPHATIDYLINOSITOL TRANSFER PROTEIN OF RAT-BRAIN BY COMPLEMENTATION OF THE YEAST SEC14 MUTATION

A second form (beta isoform) of rat phosphatidylinositol transfer prot ein cDNA was cloned by complementation of the yeast sec14 mutation fro m a rat brain cDNA expression library. The deduced sequence of the pro tein comprised 271 amino acids with a calculated molecular mass of 31, 449 Da. The deduced amino acid sequence showed 77% identity to that of the rat phosphatidylinositol transfer protein, recently reported by D ickeson et al. [Dickeson, S.K., Lim, C.N., Schuyler, G.T., Dalton, T.P ., Helmkamp, G.M., Jr., and Yarbrough, L.R. (1989) J. Biol. Chem. 264, 16557-16564]. Northern blot analysis revealed that the cDNA probe of the beta isoform hybridized to an similar to 3-kilobase RNA in various rat tissues. The mRNA was expressed abundantly in brain, kidney, live r, and lung, but in a lesser amount in testis.