Fibronectin glycosylation

Other adhesion receptors that are structurally and functionally related include the receptors for fibronectin, vitronectin, platelet glycoproteins 13b and Ilia and the VLA (very-late antigen) series. All molecules involved in adhesion recognise the RGD motif and require the divalent cations Ca2+ and Mg2+ for binding. All are dimers of glycosylated proteins with relative molecular masses 95-190 kDa. There is also some sequence homology between the /J-chain (CD18) and one chain of the fibronectin receptor. 

Adhesion proteins in this group contain an immunoglobulin domain that is composed of 90-100 amino acids arranged in a sandwich of two sheets of antiparallei strands. Some members of this family also contain fibronectin type III—like domains in addition to the immunoglobulin domain. Immunoglobulin-related adhesion proteins either can exist as transmembrane structures or can be attached to cell membranes via glycosyl phosphatidylinositol links (B4, R5). 

Zhu, B. C. R., Fischer, S. F., Pande, H., Calaycay, J., Shively, J. E., and Laine, R. A. 1984. Human placenta (fetal) fibronectin Increased glycosylation and higher protease resistance than plasma fibronectin. J. Biol. Chem. 259 3962-3970. 

To determine if differential glycosylation of fibronectin (Fn) in inflammatory synovial fluid (SF) included expression of an oncofetal epitope (Onf Fn) previously detected only on Fn derived from embryonal or neoplastic tissue [61], Fn was purified from plasma, SF and synoviocyte conditioned medium by affinity chromatography and analyzed by sodium dodeeyl sulfate-polyacrylamide gel electrophoresis and Western blotting using a monoclonal antibody (FDC-6) specific for the Onf Fn. The Onf Fn was not expressed on... 

Fig. 8. Structures of LI, MAG and PO glycoproteins. The sequences of LI (a), MAG (b) and PO (c) glycoproteins predicted from analysis of cDNA clones as well as protein in the case of PO are shown to variably include in the extracellular portions Ig-like domains, fibronectin type III repeats (hatched), a transmembrane segment and a cytoplasmic domain. Potential A-glycosylation sites are indicated (open circle). Splicing variants in the cytoplasmic domains of LI and MAG are shown (open triangle).

The functional significance in glycosylation differences between various fibronectins remains to be determined. Fibronectins with greatly altered glycosylation patterns due to inhibition of processing in cells by monensin [228,229], swainsonine [230] or in... 

The evidence is increasing that glycosylation of integrins plays important modulatory roles in the function of these molecules. In other studies it appears that the glycosylation of at least one extracellular matrix glycoprotein, namely laminin, is important in cellular adhesion mediated by integrins. So far most information on the role of carbohydrates in integrin-mediated adhesive interactions has been obtained for the fibronectin receptors... 

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