lipidtransferproteiner

Lipidtransferproteiner (LTPs) are a diverse family of proteins that facilitate the movement of lipids between cellular membranes without the need for vesicular transport. They are found in all domains of life, from bacteria to mammals, and are essential for maintaining lipid homeostasis and membrane composition. The most well‑studied mammalian members include the phosphatidylinositol transfer protein (PITP), the ceramide transfer protein (CERT), and the oxysterol‑binding protein (OSBP). Bacterial LTPs, such as the bacterial sphingolipid transfer protein (bLTP), often have simpler structures with a single lipid‑binding domain.

Structurally, LTPs typically contain a β-sandwich fold that forms a cavity for lipid binding, and many possess amphipathic helices that enable interaction with membranes. Some LTPs are soluble and shuttle lipids across the cytosol, while others embed transiently within membranes, exchanging lipids by “pop‑dance” mechanisms. The specificity of binding varies; for instance, CERT selectively transports ceramide at ER–Golgi contact sites, whereas OSBP exchanges phosphatidylinositol 4‑phosphate with cholesterol at the plasma membrane.

Functionally, LTPs contribute to membrane expansion during cell growth, signal transduction by supplying specific lipid second messengers, and the biogenesis of organelles such as the Golgi and lysosome. Dysregulation of LTPs is implicated in metabolic disorders; for example, mutated OSBP has been linked to cholesterol imbalance and atherosclerosis, while altered CERT activity can affect sphingolipid signaling in cancer. Because of their central role in lipid trafficking, LTPs are considered promising targets for therapeutic intervention in disorders of lipid metabolism.