The PITP family of phosphatidylinositol transfer proteins.

The PITP family is one of the two families of phosphoinositide transfer proteins that can bind and exchange one molecule of either phosphatidylinositol or phosphatidylcholine and facilitate the transfer of these lipids between different membrane compartments; the other is the structurally unrelated Sec14p family. PITPs have recently been shown to be critical regulators of phosphoinositides in several cellular compartments, where they participate in signal transduction and in membrane traffic. PITPs were originally defined as soluble, 35 kDa proteins that contain a single structural domain. More recently, however, the PITP domain has also been found in the larger rdgB proteins. Soluble PITPs are found in many organisms, including mammals, Caenorhabditis elegans (worms), Drosophila melanogaster (flies), and Dictyostelium discoideum (slime molds), but not in yeasts or plants. Dysfunction of PITPs leads to neurodegeneration; this highlights the need to understand the biochemical and physiological functions of these proteins in cells.