Abstract
Phosphomonoesterase and diesterase that cleave phosphatidylinositol-4-phosphate (diphosphoinositide, DPI) and phosphatidylinositol-4,5-bisphosphate (triphosphoinositide, TPI) were detected in three subfractions of purified rat brain myelin, and some properties of the enzymes were studied. Monoesterase activity was stimulated by KCl, maximally at a concentration of 25 mM, and inhibited at KCl concentrations above 50 mM. Addition of boiled pH 5 supernatant of rat brain homogenate doubled the enzymic activity; EDTA was inhibitory. The specific activities were nearly equal in the “low density”, “medium density”, and “heavy density” myelin fractions but about 30% lower than in whole brain homogenate. The monophosphatase could be solubilized by extraction with 0.2% Triton X-100. The phosphodiesterase activity was inhibited by EDTA and EGTA and not stimulated by KCl or pH 5 supernatant. Specific activities were nearly equal in whole brain and myelin but were by about 60 percent elevated in the “heavy density” over the “low density” myelin fraction. These results show that the hydrolases operative in the fast turnover of the inositide phosphate groups are distributed over the entire myelin structure.
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References
Eichberg, J., andDawson, R. M. C. 1965. Polyphosphoinositides in myelin. Biochem. J. 96:644–650.
Dawson, R. M. C. 1969. Metabolism and function of phosphoinositides in nervous tissue. Ann. N.Y. Acad. Sci. 165:774–783.
Benjamins, J. A., Miller, K., andMcKhann, G. M. 1973. Myelin subfractions in developing rat brain: Characterization and sulphatide metabolism. J. Neurochem. 20:1589–1603.
Deshmukh, D. S., Bear, W. D., andBrockerhoff, H. 1978. Polyphosphoinositide biosynthesis in three subfractions of rat brain myelin. J. Neurochem. 30:1191–1193.
Deshmukh, D. S., Kuizon, S., Bear, W. D., andBrockerhoff, H. 1981. Rapid incorporation in vivo of intracerebrally injected32Pi into polyphosphoinositides of three subfractions of rat brain myelin. J. Neurochem. 36:594–601.
Deshmukh, D. S., Kuizon, S., Bear, W. D., andBrockerhoff, H. 1980. Distribution of phosphoinositides among subfractions of rat brain myelin. Lipids 15:14–18.
Norton, W. T., andPoduslo, S. E. 1973. Myelination in rat brain: Method of myelin isolation. J. Neurochem. 21:749–757.
Hendrickson, H. S., andBallou, C. E. 1964. Ion exchange chromatography of intact brain phosphoinositides on diethylamino ethyl cellulose by gradient salt elution in a mixed solvent system. J. Biol. Chem. 239:1369–1373.
Sheltawy, A., Brammer, M., andBorrill, D. 1972. The subcellular distribution of triphosphoinositide phosphomonoesterase in guinea-pig brain. Biochem. J. 128:579–586.
Bartlett, G. R. 1959. Phosphorus assay in column chromatography. J. Biol. Chem. 234:466–468.
Martin, J. B., andDoty, D. M. 1949. Determination of inorganic phosphate: Modification of isobutyl alcohol procedure. Anal. Chem. 21:965–967.
Lowry, O. H., Rosebrough, N. J., Farr, A. L., andRandall, R. J. 1951. Protein measurement with the Folin-Phenol reagent. J. Biol. Chem. 193:265–275.
Salway, J. G., Kai, M., andHawthorne, J. N. 1967. Triphosphoinositide phosphomonoesterase activity in nerve cell bodies, neuroglia and subcellular fractions from whole rat brain. J. Neurochem. 14:1013–1024.
Cooper, P. H., andHawthorne, J. N. 1975. Phosphomonoesterase hydrolysis of polyphosphoinositides in rat kidney. Properties and subcellular localization of the enzyme system. Biochem. J. 150:537–551.
Harwood, J. L., andHawthorne, J. N. 1969. Metabolism of the phosphoinositides in guinea-pig brain synaptosomes. J. Neurochem. 16:1377–1387.
Keough, K. M., andThompson, W. 1970. Triphosphoinositide phosphodiesterase in developing brain of the rat and in subcellular fractions of brain. J. Neurochem. 17:1–11.
Tou, J. S., Hurst, M. W., Baricos, W. H., andHuggins, C. G. 1973. The hydrolysis of triphosphoinositide by a phosphodiesterase in rat kidney cortex. Arch. Biochem. Biophys. 154:593–600.
Hwan, J. C., Kuizon, S., Brockerhoff, H., andDeshmukh, D. S. 1981. Purification of myelin-bound polyphosphoinositide phosphoesterases. Trans. Am. Soc. Neurochem. 12:254.
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Deshmukh, D.S., Kuizon, S., Bear, W.D. et al. Polyphosphoinositide mono- an diphosphoesterases of three subfractions of rat brain myelin. Neurochem Res 7, 617–626 (1982). https://doi.org/10.1007/BF00965127
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DOI: https://doi.org/10.1007/BF00965127