[59] Phosphatidylinositol transfer proteins from higher eukaryotes

This chapter summarizes recent progress on small-scale isolations of phosphatidylinositol (Ptdlns) transfer protein from higher eukaryotic sources and the means of identification. Phosphatidylinositol (Ptdlns) transfer proteins comprise a class of small, cytosolic proteins, which bind single Ptdlns molecules and transport this phospholipid, without modification, between membranes. Among phospholipid transfer proteins, those which transfer Ptdlns not only are the most widely distributed in eukaryotic species and tissues, but also are the most strongly conserved in their structural features. Ptdlns transfer proteins have been purified from a broad spectrum of tissues, including human platelets and baker's yeast; they have been detected by catalytic activity measurements and immunologic techniques in at least 20 different rat tissues. The principal similarities among PtdIns transfer protein—namely, structural conservation and catalytic specificity—imply that purification and characterization may commence with any readily available tissue The principal similarities among PtdIns transfer protein—namely, structural conservation and catalytic specificity, imply that purification and characterization may commence with any readily available tissue.