PITP

PITP stands for phosphatidylinositol transfer protein, a family of small cytosolic proteins that shuttle phosphatidylinositol (PI) and phosphatidylinositol 4-phosphate (PI4P) between membrane compartments, thereby regulating phosphoinositide signaling and membrane trafficking. In humans, the best characterized members are PITP alpha (PITPNA) and PITP beta (PITPNB). These proteins carry out lipid transfer by binding PI and PI4P in a conserved lipid-binding pocket, enabling exchange of lipids between donor and acceptor membranes at sites such as the endoplasmic reticulum and Golgi apparatus, as well as at membrane contact sites.

PITP proteins support various cellular processes, including vesicle formation, endocytosis, and receptor signaling, by maintaining appropriate pools of phosphoinositides that control membrane curvature, recruitment of effector proteins, and enzyme activity of phosphoinositide kinases and phosphatases. They are considered lipid chaperones that ensure the availability of PI and PI4P to specific membranes and enzymes, thereby influencing signaling pathways and cytoskeletal dynamics.

Genetic and biochemical studies have linked PITP dysfunction or altered expression to disruptions in signaling pathways and have been investigated in the context of neurological disorders and certain cancers, though the precise mechanisms are still actively researched.

In other contexts, the acronym PITP is used for terms or programs unrelated to this protein family; such uses vary by field and are not standardized.