At the endosomes, kinases and phosphatases produces and hydrolyses specific phosphoinositides which identify endocytic membranes and allow them to recruit proteins from the cytosol that are involved in vesicle trafficking and other aspects of cellular homeostasis. Lipid mediators of signaling and recognition processes work through specific protein–lipid interactions, the levels of these signaling molecules are extremely small compared with the levels of bulk membrane …show more content…
Lipid transport between organelles to maintain their unique lipid compositions must be specific. The plasma membrane, endosomes and lysosomes rely completely on lipid transport from the organelles which actively synthesize lipids. Lipid transport can occur by various mechanisms (Fig.1a). First, lateral diffusion of lipids through membrane continuities, such as those that exist between the ER and the outer and inner nuclear membrane. Next, vesicular transport to the Golgi, the plasma membrane and endosomes, which is the major membrane transport pathway between cellular organelles in the secretory and endocytic pathways; through the budding and fusion of membrane vesicles. The uptake of fluorescent sphingolipid and phosphotidylcholine analogues in mammalian cells proceeds by various endocytic pathways. However, arresting vesicle traffic using metabolic poisons/genetic mutations does not affect the transport of emerging glycerophospholipids and cholesterol between membranes; transport of these lipids might be occurring through contact sites and by lipid transfer proteins. The contact sites could form restricted regions of lipid and protein diffusion within a given bilayer, and regions of transport protein diffusion between donor and acceptor membranes. Protein and lipid assemblies on donor and acceptor membranes as significant recognition components for