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Phospholipid Synthesis in the Squid Giant Axon: Enzymes of Phosphatidylinositol Metabolism
Author(s) -
Gould R. M.,
Spivack W. D.,
Robertson D.,
Poznansky M. J.
Publication year - 1983
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1983.tb13570.x
Subject(s) - axoplasm , phosphatidylinositol , biochemistry , diglyceride , phospholipid , diacylglycerol kinase , squid giant axon , inositol , phospholipase c , phosphatidylcholine , chemistry , kinase , biology , enzyme , microbiology and biotechnology , protein kinase c , membrane , axon , receptor
We examined the properties of several enzymes of phospholipid metabolism in axoplasm extruded from squid giant axons. The following synthetic enzymes, CDP‐diglyceride: inositol transferase (EC 2.7.8.11), ATP:diglyceride phosphotransferase, diglyceride kinase (EC 2.7.2.‐), and phosphatidylinositol kinase (EC 2.7.1.67), were all present in axoplasm. Phospholipid exchange proteins, which catalyzed the transfer of phosphatidylinositol and phosphatidylcholine between membrane preparations and unilamellar lipid vesicles, were also found. However, we did not find conditions under which the synthesis of CDP‐diglyceride, phosphatidyl serine, and phosphatidylinositol‐4,5‐diphosphate could be measured. Subcellular fractionation by differential centrifugation showed that the axoplasmic inositol transferase and phosphatidylinositol kinase activities were largely “microsomal,” while the diglyceride kinase and exchange protein activities were primarily “cytosolic.”