Mammalian hepatic lectin

The mammalian hepatic lectin (also referred to as the asialoglycoprotein receptor) is found on the surface of liver cells. The protein directs the clearance from the serum... 

Mammalian hepatic lectin (HL), also known as asialoglycoprotein receptor (ASGP-R), is a type II transmembrane glycoprotein present both on the plasma membrane and internal membranes of hepatocytes. The cell surface receptor binds asialoglycoproteins that carry many exposed Gal/GalNAc residues and intemaUzes them. 

Hepatic lectins belong to a group of lectins known as C-type, so named because they require calcium for ligand binding, and it is now known that they share a structurally homologous carbohydrate-recognition domain [15]. All mammalian hepatic lectins so far examined are composed of two types of subunit, HL-1 and HL-2, which share a considerable homology in amino acid sequence and the same polypeptide domain construct. They are composed of, from the N-terminal end ... 

Interestingly as shown in Table 1, hepatic lectins from different animal families express different carbohydrate specificities. Therefore, the designation of asialoglycoprotein receptor for HL does not apply for non-mammalian species. It is also to be noted that in addition to parenchymal cells (hepatocytes), Kupffer cells and endothelial cells of the liver have receptors for other sugars, such as Man and GlcNAc. Lectins identical or very similar to HLs were also found to exist in the extrahepatic tissues such as testis/sperm [5-8], kidney [9], mesangial cells [10] and... 

The hepatic lectin is reported to be nearly absent in mammalian fetal liver but rises to adult levels during the early postpartum period. Low levels of asialoglycoprotein receptor in 18-day-old fetal liver correlated to a three-fold higher level of total asialoglycoproteins in fetal serum compared with those of adults. The serum asialoglycoproteins decreased to adult values as more hepatic lectin is generated later in development [29],... 

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