Glycoproteins receptor binding

LDL (apo B-lOO, E) receptors occur on the cell surface in pits that are coated on the cytosolic side of the cell membrane with a protein called clathrin. The glycoprotein receptor spans the membrane, the B-lOO binding region being at the exposed amino terminal end. After binding, LDL is taken up intact by endocytosis. The apoprotein and cholesteryl ester are then hydrolyzed in the lysosomes, and cholesterol is translocated into the cell. The receptors are recycled to the cell surface. This influx of cholesterol inhibits in a coordinated manner HMG-CoA synthase, HMG-CoA reductase, and, therefore, cholesterol synthesis stimulates ACAT activ-... 

Xin KQ, Hamajima K, Hattori S, Cao XR, Kawamoto S, Okuda K (1999) Evidence of HIV type 1 glycoprotein 120 binding to recombinant N-methyl-D-aspartate receptor subunits expressed in a baculovirus system. AIDS Res Hum Retroviruses 15(16) 1461-1467... 

Rizzuto CD, Wyatt R, Hemandez-Ramos N, et al. A conserved HIV gpl20 glycoprotein structure involved in chemokine receptor binding [see comments]. Science 1998 280(5371) 1949-1953. 

This polyionic structure can provide protection against HIV infection by binding to the gpl20 glycoprotein receptor on the vims surface. The normal course of infection of healthy cells with HIV begins when the gpl20 protein on the surface of the vims binds to the CD4 receptor on the surface of the healthy cell [71b]. 

Thrombus formation at the site of the damaged vascular wall (EC endothelial cell) and the role of platelets and clotting factors. Platelet membrane receptors include the glycoprotein (GP) la receptor, binding to collagen (C) GP lb receptor binding, von Willebrand factor (vWF), and GP... 

Abciximab was the first commercially available GPIIb/llla receptor inhibitor. Abciximab is a monoclonal Fab immunoglobulin fragment that binds to the glycoprotein receptor on the platelet membrane. The half-life of abciximab... 

As mentioned in Section 17.2.1, HA is a spike glycoprotein anchored to the virus lipid membrane [50], This glycoprotein functions as a receptor-binding protein and is responsible for the first step of viral infection when it binds to sialic acid residues of receptor glycoproteins on host cells [18]. When the virus is endocytosed into the cell, the low pH (5-6) changes the structure of HA, and this new fusion-active state triggers the fusion of the viral membrane and the endosome membrane, ultimately allowing entry of the viral nucleocapsid into the cytosol of the host cell [18]. 

Transferrin is a single-chain glycoprotein that binds 2 g-atoms of ferric iron per mole of protein. The iron is chelated via tyrosyl and histidyl residues, and the complex is extremely stable at physiologic pH. The function of transferrin is to transport iron throughout the human organism, especially to the immature red cells, which cannot effectively acquire iron for the biosynthesis of hemoglobin unless it is presented to them in combination with transferrin. Specific transferrin receptors are present on the surface of such immature red cells as well as in all other tissues. Receptor-mediated endocytosis (see Chapter 9) is believed to be the main means of transferrin-bound iron entry into cells. Transferrin is also believed to be antimicrobial because it withholds iron from microorganisms. 

Cross-linking has also been used to detect GH receptors/binding sites in other tissues and species. The main receptor component detected in rat liver and the human IM9 cell line (which binds human GH specifically) is rather larger (Mt = 100000) than that seen in rabbit liver [35,37], Multiple cross-linked GH-receptor components have been detected in rat hepatocytes, but these are probably all related to aggregates of glycoprotein subunits of Mr 100000 held together by disulphide bonds and non-covalent interactions [37]. 

Platelet glycoprotein Ilb-IIIa receptor binding is given as fmol 125I-fibrinogen/108 platelets or 125I-fibrinogen molecules bound per platelet. 

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