text: The human asialoglycoprotein receptors composed of two units, H1 and H2. Each of these units have their N-terminus within the cytoplasm of a liver cell, and a carbohydrate recognition domain (CRD) on the extracellular side. The CRD functions to bind to asialoglycoproteins through a calcium ion-mediated interaction. In particular, the hydroxyl groups of the terminal sugars (usually galactose) of the asialoglycoprotein form hydrogen bonds with the CRD of the asialoglycoprotein receptor; proper positioning and facilitation of these hydrogen bonds is caused by the presence of Ca2+.