Lipids are fatty acids and their derivatives, and substances related biosynthetically or functionally to these compounds. Lipids are diverse group of organic compounds including fats, oils, hormones, and certain components of membranes that are grouped together and mainly amphipathic. The variation in head groups and aliphatic chains allows the presence of more than 1000 different lipid species in any eukaryotic cell. Different types of lipid include Phospholipids, Sphingolipids and Cholesterol. Lipid plays a role in many functions of the cell such as the signaling and the conversion of energy, membrane fluidity and compartmentalization of cellular organelles. The movement of lipids from their sites of synthesis to definitive intracellular
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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
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