Asialoglycoprotein

Lodish, H. F., 1991. Recognition of complex oligosaccharides by die mnl-tisnbnnit asialoglycoprotein receptor. Trends in Biochemical Sciences 16 374-2T11. 

FIGURE 9.30 Progressive cleavage of sialic acid residues exposes galactose residues. Binding to the asialoglycoprotein receptor in the liver becomes progressively more likely as more Gal residues are exposed. 

Proteins are degraded by both ATP-dependent and ATP-independent pathways. Ubiquitin targets many intracellular proteins for degradation. Liver cell surface receptors bind and internalize circulating asialoglycoproteins destined for lysosomal degradation. 

Figure 46-5 shows a variety of ways in which proteins are distributed in the plasma membrane, in particular, the amino terminals of certain proteins (eg, the LDL receptor) can be seen to be on the extracytoplasmic face, whereas for other proteins (eg, the asialoglycoprotein receptor) the carboxyl terminals are on this face. To explain these dispositions, one must consider the initial biosynthetic events at the ER membrane. The LDL receptor enters the ER membrane in a manner analogous to a secretory protein (Figure 46-4) it partly traverses... 

Figure 46-5. Variations in the way in which proteins are inserted into membranes. This schematic representation, which illustrates a number of possible orientations, shows the segments of the proteins within the membrane as a-helicesand the other segments as lines. The LDL receptor, which crosses the membrane once and has its amino terminal on the exterior, is called a type I transmembrane protein. The asialoglycoprotein receptor, which also crosses the membrane once but has its carboxyl terminal on the exterior, is called a type II transmembrane protein. The various transporters indicated (eg, glucose) cross the membrane a number of times and are called type III transmembrane proteins they are also referred to as polytopic membrane proteins. (N, amino terminal C, carboxyl terminal.) (Adapted, with permission, from Wickner WT, Lodish HF Multiple mechanisms of protein insertion into and across membranes. Science 1985 230 400. Copyright 1985 by the American Association for the Advancement of Science.)...

THE MAMMALIAN ASIALOGLYCOPROTEIN RECEPTOR IS INVOLVED IN CLEARANCE OF CERTAIN GLYCOPROTEINS FROM PLASMA BY HEPATOCYTES... 

C-type lectins Characterized by a Ca +-dependent carbohydrate recognition domain (CRD) includes the mammalian asialoglycoprotein receptor, the selectins, and the mannosebinding protein... 

Hepatocytes are a cell-type, of particular interest in tissue engineering due to the regenerative capacity of the liver and the quantity of waiting liver transplant recipients, for which there are too few available organ donors. While the asialoglycoprotein receptor on hepatocytes does not... 

Dini, L., Autuoii, F., Lentini, A., Oliverio, S., Piacentini, M., 1992, The clearance of apoptotic cells in the hver is mediated by the asialoglycoprotein recetpor, FEES Lett. 296 174-178. 

Liver Hepatocytes Lactosaminated (H)SA Arabinogalactan Asialoglycoproteins Rat, man Man Rat, man Hepatitis B and C Liver cancer... 

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