Nervous tissue glycoproteins

Fig. I. Core structures of the carbohydrate units of nervous tissue glycoproteins. The structures are based on analytical data on rat brain glycoproteins and on assumptions of structural similarity with glycan cores from other sources. The main positions of variable or incomplete glycosylation are indicated by arrows. The approximate molar proportions of the glycans in rat brain and the mode of interaction with concanavalin A-Sepharose are indicated (the bisecting GicNAc residue affects the interaction of the diantennary glycans with concanavalin A) [9].

Fig. 2. Terminal sugar sequences of the N-linked glycans of nervous tissue glycoproteins. For references, see ref. [3].

Fig. 3. Structures of the classical 0-linked glycans of nervous tissue glycoproteins [3,18,31,32],...

Chapter 3. Carbohydrate units of nervous tissue glycoproteins... 

Margolis, R. K., and Margolis, R. U., 1983, Distribution and characteristic of polysialosyl oligosaccharides in nervous tissue glycoprotein, Biochem. Biophys. Res. Commun. 116 889-894. 

Salivary agglutinin, identical to lung glycoprotein-340 (gGP-340) and a protein with an unrelated function in nervous tissue (DMBT1), is a highly conserved bacterial receptor. In the lungs and saliva where it is secreted, it attaches to many different bacteria, including... 

A disaccharide unit with an a-galactose moiety, GaI(al-3)GalNAc has been discovered as an O-linked unit in the brains of the rat, rabbit, hen, frog and fish [31], It seems to be concentrated in nervous tissue, because it was not found in five other tissues of the rat. Other sources where the disaccharide has been discovered are the muscle and the adrenal medulla [32] and human teratocarcinoma cells [33]. Its enrichment in brain tissue together with its occurrence in roughly similar amounts in different animal species may suggest a role important for nervous tissue function. However, no information of its possible role or occurrence in specified glycoprotein molecules is yet available. 

The Ig-superfamily contains many proteins involved in immune recognition such as products of the MHC complex and accessory molecules [53]. In addition there are ten or more members associated mainly with nervous tissues in mature animals and several others in non-nervous tissue that are important factors in cell-cell and cell-substratum adhesion in non-immune cells. See [54] and [55] for detailed discussion of other aspects of Ig-superfamily glycoproteins. All of the cell adhesion glycoproteins in the family contain a variable number of Ig-like domains of about one hundred amino-acid residues, usually but not always defined within a pair of disulfide-bonded cysteine residues, and of the C2 type fold. In many cases the molecules contain variable numbers of another type of modular sequence known as the fibronectin type III repeat, sinee it was discovered in fibroneetin. In the following discussion, some principles of the structure and functions of this large family of cell adhesion molecules will be considered with particular emphasis on the interplay between different members in adhesion and modulation of adhesive interactions by carbohydrates. 

Fibronectin extravasation 440 kDa glycoprotein of the ECM that binds to integrins and ECM components such as fibrin, heparan sulfete proteoglycans, and collagen Fibronectin extravasation into the nervous tissue can be used as a marker of altered vascular permeability Can be performed on parafiin sections or cryosections [62] Cortical cold injury [39], hypertensive brain injury [40], carotid infusion of hyperosmolar solutions [41]... 

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