[A new method for studying the lipid transport in vitro: the protein with molecular weight 45-kDa from the rat olfactory epithelium--specific carrier of phosphatidylinositol 3,4,5-triphosphate].

A new method for studying the lipid-protein interactions in vitro is developed. It enables the study of the transporting activity of a protein toward a lipid ligand, including the case with an unknown lipid type. The method can be considered as a variant of partition three-phase chromatography with two stationary (donor and acceptor) phases and one mobile phase. The protein under study is dissolved in an aqueous mobile phase and induces a specific delivery of a lipid to the acceptor lipid layer. The transported lipid is identified in the Folch lipid extracts from the acceptor layer and aqueous phase. The secretory protein with M 45 kDa from the rat olfactory epithelium is shown to be a carrier of phosphatidylinositol 3,4,5-triphosphate. Our approach opens up new possibilities in the study of lipid-protein interactions in vitro and has a number of advantages over the methods now used for these purposes.