lipidtransfer

Lipid transfer refers to the movement of lipid molecules between membranes or compartments, occurring through vesicular transport or non-vesicular mechanisms. It is essential for organizing membrane composition and enabling lipid signaling and metabolism within cells.

Non-vesicular lipid transfer is mediated by lipid transfer proteins (LTPs) that shuttle specific lipids between membranes at sites of close membrane contact. LTPs extract a lipid from a donor membrane, shield it within a hydrophobic pocket or binding domain, and deliver it to an acceptor membrane. Examples include CERT, which transfers ceramide from the endoplasmic reticulum to the Golgi apparatus for sphingolipid synthesis, and the OSBP-related protein family, which can exchange cholesterol and phosphatidylinositol 4-phosphate between the ER and the Golgi. START domain proteins and phosphatidylinositol transfer proteins (PITPs) also participate in lipid transfer processes. Transfer can be driven by lipid gradients, binding affinities, and regulatory interactions at membrane contact sites.

Vesicular transport moves lipids as part of membrane bilayers within vesicles that bud from one compartment and fuse with another. This route co-transports proteins and other cargo but can be less selective for individual lipids compared with non-vesicular routes. Vesicular trafficking helps establish and maintain organelle identity and membrane asymmetry.

Functional significance includes maintaining distinct lipid compositions among organelles, supporting lipid signaling pathways, and contributing to lipid metabolism and energy homeostasis. Dysregulation of lipid transfer is linked to metabolic disorders and certain neurodegenerative diseases, highlighting its importance in cellular physiology.