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Quisqualate‐Stimulated Phosphatidylinositol Breakdown in Rat Cerebellar Membranes
Author(s) -
Llahi Silvia,
Claro Enrique,
Fain John N.
Publication year - 1992
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.1471-4159.1992.tb09776.x
Subject(s) - gtp' , phosphatidylinositol 4,5 bisphosphate , phosphatidylinositol , biochemistry , chemistry , excitatory postsynaptic potential , guanosine , phospholipase c , biology , receptor , signal transduction , enzyme
The effect of quisqualate, an excitatory amino acid agonist, on the breakdown of exogenously added phosphatidylinositol was investigated in a membrane preparation from the cerebellum of young rats. Quisqualate stimulated phospholipase C activity in a dose‐dependent manner in the presence of guanosine 5′‐ O ‐(3‐thiotriphosphate) (GTP γ S). Half‐maximal activation of the quisqualate response required 0.15 γ M GTP γ S and was optimal at a free Ca 2+ concentration of 300 n M. Phosphoinositide breakdown was also stimulated by quisqualate using either exogenous phosphatidylinositol 4,5‐bisphosphate or endogenous labeled phosphoinositides as the substrate for phospholipase C in cerebellar membranes. In the presence of guanine nucleotides, other excitatory amino acid agonists, such as l ‐glutamate, trans ‐ d , l ‐1‐aminocyclo‐pentyl‐1,3‐dicarboxylic acid, and ibotenate, but not N ‐methyl‐ d ‐aspartate, stimulated phosphatidylinositol breakdown. However, quisqualate displayed the highest response among these excitatory amino acid agonists. These data indicate that there is a direct activation of phosphoinositide‐specific phospholipase C by excitatory amino acids through a process dependent on the presence of guanine nucleotides.