Plants hydroxyproline-rich glycoproteins

Cassab, G.I., Nieto-Sotelo, J., Cooper, J.B., Van Holst, G.-J. Varner, J.E. (1985). A developmentally regulated hydroxyproline-rich glycoprotein from the cell walls of soybean coats. Plant Physiology, 77, 532-5. 

Esquerre-Tugaye, M. T, Lafitte, C., Mazau, D., Toppan, A., and Touze, A., 1979, Cell surfaces in plant-microorganism interactions. II. Evidence for the accumulation of hydroxyproline-rich glycoproteins in the cell wall of diseased plants as a defense mechanism. Plant Physiol. 64 320-326. 

Plants contain at least three classes of hydroxyproline-rich glycoproteins 1) the cell wall proteins, 2) the arabinogalactan proteins, and 3) lectins. According to Cooper and Varner (23) the hydroxyproline-rich glycoprotein of the cell wall of carrots is secreted from the cytoplasm as a soluble monomer that slowly becomes insolubilized. 

Hood, E. E., Shen, Q. X., and Varner, J. E. A developmentally regulated hydroxyproline-rich glycoprotein in maize pericarp cell walls. Plant Physiology, 138-142, ISSN 1532-2548 (1988). 

Several classes of proteins have been identified in plant walls and termed structural proteins , implying an absence of enzymatic function (reviewed in [15]). These include hydroxyproline-rich glycoproteins (HRGPs), proline-rich proteins (PRPs), glycine-rich proteins (GRPs) and arabinogalactan proteins (AGPs). Primary walls also contain numerous enzymes, and still other proteins with no known function [68]. 

Several of the hydroxyproline-rich glycoproteins extracted from plant tissues have carbohydrate-binding activity these glycoproteins have the characteristics of lectins. These lectins or lectin-like glycoproteins have compositions which are similar to that of the cell wall hydroxyproline-rich glycoprotein. 

M. J. Kieliszewski, M. O Neill, J. Leykam. R. Orlando. Tandem mass spectrometry and structural elucidation of glycopeptides from a hydroxyproline-rich plant cell wall glycoprotein indicate that contiguous hydroxyproline residues are the major sites of hydroxyproline O-arabinosylation. Jour. Biol. Chem. 1995,270, 2541-2549. 

Although the principal cell wall components of plants are carbohydrates, proteins account for 5-10% of the mass.165 Predominant among these are glycoprotein extensins. Like collagen, they are rich in 4-hydroxyproline which is glycosylated with arabi-nose oligosaccharides and galactose (p. 181). Other... 

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