Since the discovery of the low-density lipoprotein receptor (LDLR) and its association with familial hypercholesterolemia in the early 1980s, a family of structurally related proteins has been discovered that has apolipoprotein E as a common ligand, and the broad functions of its members have been described. LRP2, or megalin, is a member of the LDLR family and was initially called gp330. Megalin is an endocytic receptor expressed on the apical surface of several epithelial cells that internalizes a variety of ligands including nutrients, hormones and their carrier proteins, signaling molecules, morphogens, and extracellular matrix proteins. Once internalized, these ligands are directed to the lysosomal degradation pathway or transported by transcytosis... |