Cloning of a cDNA Encoding a Second Phosphatidylinositol Transfer Protein of Rat Brain by Complementation of the Yeast sec14 Mutation

A second form (β isoform) of rat phosphatidylinositol transfer protein cDNA was cloned by complementation of the yeast sec14 mutation from a rat brain cDNA expression library. The deduced sequence of the protein 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 Dickeson et al. [Dickeson, S.K., Lim, C.N., Schuyler, G.T., Dalton, T.P., Helmkamp, G.M., Jr., & Yarbrough, L.R. (1989) J. Biol. Chem. 264, 16557–16564]. Northern blot analysis revealed that the cDNA probe of the β isoform hybridized to an ∼3-kilobase RNA in various rat tissues. The mRNA was expressed abundantly in brain, kidney, liver, and lung, but in a lesser amount in testis.