Attachment glycoprotein

This group of diseases is characterized by the accumulation of a specific isoform of the normal prion protein (PrP), termed PrPSc, which seems to be the main infectious agent. PrPSc is derived by a conformational change from the isoform of the prion protein PrPC. PrPSc is a copper-binding glycoprotein attached to the cell membrane of neuronal cells [21]. The PrPSc form is protease resistant, has a beta-sheet structure and possesses a tendency to polymerization [22]. 

Core pentasaccharide Man(a1-6)[Man(a1-3)]Man()J1-4)GlcNAc(/S1-4)GlcNAc of JV-glycoproteins attached to the consensus sequence Asn-Xaa-Ser/Thr. Solid arrows indicate the points of attachment of the outer ami saccharides forming carbohydrate chains, caiied antennae, in addition, the inner-core may be substituted by several monosaccharides dashed arrows)... 

The enzyme catalyzes the cleavage of terminal sialic acid from adjacent sugar residues. Neuraminidase and hemagglutinin are the two glycoproteins attach to the influenza viral membrane. They make up the antigenic surface of the virus, and changes in these proteins form the basis for evasion of immune recognition from previous infections. Data extracted from Davies et ai (1990). Individual references are a) Sheriff et al. (1987) b) Padlan et al. (1989) c) Amit et al. (1986) d) Tulip et oL (1989). 

Glycoprotein A long, spikelike molecule made of carbohydrate and protein that projects beyond the surface of a cell or viral envelope some viral glycoproteins attach the virus to receptor sites on host cells, while other said fusion of viral and cellular membranes. 

Glycohpids (5,14) are primarily glycosphingoHpids, molecules that have oligosaccharide groups attached to ceramide [104404-17-3]. They are present, at least in small amounts, in the membranes of most, if not all, tissues. They too, like cell-membrane glycoproteins, are recognition deterrninants. 

Glycoprotein (Section 25.16) Aprotein to which carbohydrate molecules are attached by covalent bonds. 

Vitamin B12 is special in as far as its absorption depends on the availability of several secretory proteins, the most important being the so-called intrinsic factor (IF). IF is produced by the parietal cells of the fundic mucosa in man and is secreted simultaneously with HC1. In the small intestine, vitamin B12 (extrinsic factor) binds to the alkali-stable gastric glycoprotein IF. The molecules form a complex that resists intestinal proteolysis. In the ileum, the IF-vitamin B 12-complex attaches to specific mucosal receptors of the microvilli as soon as the chymus reaches a neutral pH. Then either cobalamin alone or the complex as a whole enters the mucosal cell. 

Stress fibers are parallel bundles of actin filaments that develop in the cytoplasm of fibroblasts from the cortical actin network in response to mechanical tension. These often bind to the plasma membrane at focal contacts and, through transmembrane linker glycoproteins, to the extracellular matrix. Thus, actin filaments of stress fibers indirectly Join to the inner face of the plasma membrane through molecular assemblies of attachment proteins, which include an actin-capping protein, a-actinin, vinculin, and talin (Small, 1988). 

Fibronectin receptor is a two-chain glycoprotein of the integrin family that serves as a transmembrane linker by binding to talin on the cytoplasmic side and to fibronectin on the external side of the membrane. The pull exerted by stress fibers on attached structures may be produced by bipolar assemblies of nonmuscle myosin molecules producing a sliding of actin filaments of opposite polarity. 

Location of the Position of Attachment of a Glycan on the Polypeptide Backbone of a Glycoprotein... 

Glycoprotein A protein containing sugar molecules attached to its polypeptide chain. 

Fucose Deoxyhexose Fuc GDP-Fuc May be external in both N- and 0-linked glycoproteins or internal, linked to the GIcNAc residue attached to Asn in N-linked species. Can also occur internally attached to the OH of Ser (eg, in t-PA and certain clotting factors). 

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