Receptor interactions controlling lipoprotein metabolism.
Lipoprotein receptors play a central role in lipoprotein metabolism and a major role in cholesterol homeostasis. The most completely characterized lipoprotein receptor is the LDL (low density lipoprotein) or apo-B,E(LDL) receptor. The apo-B,E(LDL) receptor is present on both hepatic and extrahepatic cells and is responsible for the metabolism of a major portion of plasma LDL. Binding and internalization of LDL particles by this receptor initiates a series of intracellular events, resulting in the regulation of cellular cholesterol metabolism. In addition to the apo-B on LDL interacting with the apo-B,E(LDL) receptor, the apo-E on apo-E-containing lipoproteins is also capable of interacting and regulating intracellular cholesterol metabolism. The liver has also been shown to contain a second distinct lipoprotein receptor that is specific for apo-E. This receptor has been demonstrated on hepatic membranes from humans, dogs, and swine and is referred to as the apo-E receptor. This receptor may be responsible for the clearance of chylomicron remnants from plasma by the liver and may participate in reverse cholesterol transport. Thus, apo-E is a major determinant in lipoprotein metabolism and cholesterol homeostasis. The receptor binding properties of apo-E are well characterized, and a series of structural variants, several with lipoprotein binding defects, have been identified. Studies of the binding activity of these receptor-defective apo-E variants have helped to define the receptor binding domain of apo-E.(ABSTRACT TRUNCATED AT 250 WORDS)
D000595:Amino Acid Sequence; D000818:Animals; D001057:Apolipoproteins E / Q000378:metabolism; D001665:Binding Sites; D002784:Cholesterol / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D008074:Lipoproteins / Q000378:metabolism*; D008954:Models, Biological; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018110:Receptors, Lipoprotein; D013329:Structure-Activity Relationship
D001057:Apolipoproteins E; D008074:Lipoproteins; D011956:Receptors, Cell Surface; D018110:Receptors, Lipoprotein; D002784:Cholesterol