Abstract
Glycoproteins that contain phosphohexosyl groups were found to be present in the myelin- and synaptosomal-enriched fractions as well as in the microsomes of rat brain. The kinetics of flow of intraperitoneally injected [32P]phosphate suggests that the phosphate is enzymatically added in structures found in the microsomal fraction. The newly synthesized phosphoglycoproteins then appear in the soluble fraction of the synaptosomes and in the cytosol, prior to incorporation into the membranes of the synaptosomes and myelin. Phosphoglycopeptides recovered from the phosphoglycoprotein contain 3 Mannose units per N-acetylglucosamine residue; one of the mannose residues is phosphorylated. [13C]NMR studies indicate that the phosphoglycopeptides contain a chitobiose group and more than four sugar residues. Thus, the phosphomannoglycopeptides from rat brain contain an average of 2 N-acetylglucosamine, 6 mannose, and two phosphate moieties per oligosaccharide chain. Enzymatic treatment with α-mannosidase failed to remove the phosphomannose, although some mannose residues were released. Thus, the phosphorylated mannose is not removed by the glycosidase and terminal nonphosphorylated mannose residues are present in the oligosaccharide. The phosphate residues are removed by treatment with alkaline phosphatase.
Similar content being viewed by others
References
Benjamins, J. S., Miller, K., andMcKhann, G. M. 1973. Myelin subfractions in developing rat brain: Characterization and sulphatide metabolism. J. Neurochem. 20:1589–1603.
Boas, N. F. 1953. Method for the determination of hexosamine in tissues. J. Biol. Chem. 204:553–563.
Brunngraber, E. G. 1979. Neurochemistry of Aminosugars. Neurochemistry and Neuropathology of the Complex Carbohydrates, Charles C Thomas Publisher, Springfield, IL.
Brunngraber, E. G., andBrown, B. D. 1964. Heterogeneity of sialomucopolysaccharides prepared from whole rat brain. Biochim. Biophys. Acta 83:357–360.
Brunngraber, E. G., Brown, B. D., andHof, H. 1971. Determination of gangliosides, glycoproteins, and glycosaminoglycans in brain tissue. Clin. Chim. Acta 32:159–170.
Conchie, J., andStrachan, I. 1978. The carbohydrate units of ovalbumin: complete structures of three glycopeptides. Carbohyd. Res. 63:193–213.
Davis, L. G., Javaid, J. I., andBrunngraber, E. G. 1976. Identification of phosphoglycoproteins obtained from rat brain. FEBS Lett. 65:30–34.
Davis, L. G., Costello, A. J. R., Javaid, J. I., andBrunngraber, E. G. 1976.31PNMR studies on the phosphoglycopeptides obtained from rat brain glycoproteins. FEBS Lett. 65:35–38.
Distler, J., Hieber, V., Sahagian, G., Schmickel, R., andJourdian, G. W. 1979. Identification of mannose 6-phosphate in glycoproteins that inhibit the assimilation of β-galactosidase by fibroblasts. Proc. Natl. Acad. Sci. USA 76:4235–4239.
Grossfeld, R. M., andShooter, E. M. 1971. A study of the changes in protein composition of mouse brain during ontogenetic development. J. Neurochem. 18:2265–2278.
Hasilik, A., andNeufeld, E. F. 1980. Biosynthesis of lysosomal enzymes in fibroblasts. Phosphorylation of mannose residues. J. Biol. Chem. 255:2946–2952.
Heppel, L. A. 1955. Intestinal phosphomonoesterase. Meth. Enzymol. 2:530–533.
Hof, H. I., Susz, J. P., Javaid, J. I., andBrunngraber, E. G. 1975. Con A-binding glycopeptides from rat brain glycoproteins. Neurobiology 5:347–354.
Javaid, J. I., Hof, H. I., andBrunngraber, E. G. 1975. Preparation and properties of Con A-binding glycopeptides derived from rat brain glycoproteins. Biochim. Biophys. Acta 404:74–82.
Kaplan, A., Achord, D. T., andSly, W. S. 1977. Phosphohexosyl components of a lysosomal enzyme are recognized by pinocytosis receptors on human fibroblasts. Proc. Natl. Acad. Sci. USA 74:2026–2030.
Light, A. 1967. Leucine aminopeptidase. Meth. Enzymol. 11:426–428, 1967.
Lowry, O. H., Rosebrough, N. J., Farr, A. L., andRandall, R. J. 1951. Protein measurement with Folin-phenol reagent. 1951. J. Biol. Chem. 193:265–275.
Natowicz, M. R., Chi, M. Y., Lowry, O. H., andSly, S. 1979. Enzymatic identification of mannose 6-phosphate on the recognition marker for receptor-mediated pinocytosis of β-glucuronidase by human fibroblasts. Proc. Natl. Acad. Sci. USA 76:4322–4326.
Porter, W. H. 1975. Application of nitrous acid in determination of hexosamine to the simultaneous GLC determination of neutral and aminosugars in glycoproteins. Anal. Biochem. 63:27–43.
Routtenberg, A., George, D. R., Davis, L. G., andBrunngraber, E. G. 1974. Memory consolidation and fucosylation of crude synaptosomal glycoproteins resolved by gel electrophoresis. A regional study. Behav. Biol. 12:461–475.
Sando, G. N., andNeufeld, E. F. 1977. Recognition and receptor-mediated uptake of a lysosomal enzyme, α-L-iduronidase, by cultured human fibroblasts. Cell 12:619–625.
Schranger, J., andOates, M. D. G. 1968. The carbohydrate components of hydrolyzates of gastric secretion and extracts from mucous glands of the gastric mucosa and antrum. Biochem. J. 106:523–529.
Susz, J. P., Hof, H. I., andBrunngraber, E. G. 1973. Isolation of Con A-binding glycoproteins from rat brain. FEBS Lett. 32:289–292.
Suzuki, K. 1965. The pattern of mammalian brain gangliosides. Evaluation of the extraction procedures, post-mortem changes, and the effect of formalin fixation. J. Neurochem. 12:629–638.
Tabas, I., andKornfeld, D. 1980. Biosynthetic intermediates containing high mannose oligosaccharides with blocked phosphate residues. J. Biol. Chem. 255:6633–39.
Whittaker, V. P., Michaelson, I. A., andKirkland, R. J. A. 1964. The separation of synaptic vesicles from nerve ending particles (“Synaptosomes”). Biochem. J. 90:293–303.
Varki, A., andKornfeld, S. 1980. Identification of a rat liver α-N-acetylglucosaminyl phosphodiesterase capable of removing “blocking” α-N-acetylglucosaminyl residues from phosphorylated high mannose oligosaccharides of lysosomal enzymes. J. Biol. Chem. 255:8398.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Brunngraber, E.G., Davis, L.G. & Somawardhana, C.W. The metabolism and structure of phosphoglycoproteins in rat brain. Neurochem Res 7, 1243–1256 (1982). https://doi.org/10.1007/BF00965895
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00965895