The asialoglycoprotein receptors (ASGPR) are lectins which bind asialoglycoprotein and glycoproteins from which a sialic acid has been removed to expose galactose residues.  The receptors, which are integral membrane proteins and are located on mammalian hepatocytes (liver cells), remove target glycoproteins from circulation. The asialoglycoprotein receptor has been demonstrated to have high expression on the surface of hepatocytes and several human carcinoma cell lines It is also weakly expressed by glandular cells of the gallbladder and the stomach. Lactobionic acid has been used as a targeting moiety for drug delivery to cells expressing asialoglycoprotein receptors.
The asialoglycoprotein receptor contains two subunits, asialoglycoprotein receptor 1 (ASGR1) and  asialoglycoprotein receptor 2 (ASGR2). These subunits may form different quaternary forms such as dimers, trimers, tetramers to allow for specific substrate binding or endocytosis. ASGR 1 is the major subunit and has 8 exons and is roughly 6 kb in length. ASGR 2 is the minor subunit and has 9 exons and is about 13.5 kb long.