The glycan substrate of the cytosolic (Pho 2) phosphorylase isozyme from Pisum sativum L.: identification, linkage analysis and subcellular localization
| Autor: | Simon Poeste, Nora Eckermann, Joerg Fettke, Markus Pauly, Martin Steup |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Glycan
animal structures Chloroplasts Plant Science Polysaccharide Substrate Specificity Glycogen phosphorylase chemistry.chemical_compound Cytosol Polysaccharides Glycosyltransferase Genetics Glycosyl Plant Proteins chemistry.chemical_classification biology Protoplasts Glycogen Phosphorylase Peas food and beverages Glycosidic bond Cell Biology Chloroplast Isoenzymes chemistry Biochemistry Galactose biology.protein Subcellular Fractions |
| Zdroj: | The Plant journal : for cell and molecular biology. 39(6) |
| ISSN: | 0960-7412 |
| Popis: | The subcellular distribution of starch-related enzymes and the phenotype of Arabidopsis mutants defective in starch degradation suggest that the plastidial starch turnover is linked to a cytosolic glycan metabolism. In this communication, a soluble heteroglycan (SHG) from leaves of Pisum sativum L. has been studied. Major constituents of the SHG are galactose, arabinose and glucose. For subcellular location, the SHG was prepared from isolated protoplasts and chloroplasts. On a chlorophyll basis, protoplasts and chloroplasts yielded approximately 70% and less than 5%, respectively, of the amount of the leaf-derived SHG preparation. Thus, most of SHG resides inside the cell but outside the chloroplast. SHG is soluble and not membrane-associated. Using membrane filtration, the SHG was separated into a10 kDa and a10 kDa fraction. The latter was resolved into two subfractions (I and II) by field-flow fractionation. In the protoplast-derived10 kDa SHG preparation the subfraction I was by far the most dominant compound. beta-Glucosyl Yariv reagent was reactive with subfraction II, but not with subfraction I. In in vitro assays the latter acted as glucosyl acceptor for the cytosolic (Pho 2) phosphorylase but not for rabbit muscle phosphorylase. Glycosidic linkage analyses of subfractions I and II and of the Yariv reagent reactive glycans revealed that all three glycans contain a high percentage of arabinogalactan-like linkages. However, SHG possesses a higher content of minor compounds, namely glucosyl, mannosyl, rhamnosyl and fucosyl residues. Based on glycosyl residues and glycosidic linkages, subfraction I possesses a more complex structure than subfraction II. |
| Databáze: | OpenAIRE |
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