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Interaction of GTP‐binding proteins with calmodulin
Author(s) -
Asano Tomiko,
Ogasawara Nobuaki,
Kitajima Satoko,
Sano Mamoru
Publication year - 1986
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(86)80729-3
Subject(s) - calmodulin , gtp' , phosphodiesterase , g protein , pertussis toxin , gtp binding protein regulators , cyclic nucleotide phosphodiesterase , biochemistry , binding protein , chemistry , biology , biophysics , enzyme , receptor , gene
Two GTP‐binding proteins (G i and G o ), which were the substrates for islet‐activating protein, pertussis toxin, were purified from bovine cerebral cortical membranes. Both G i and G o completely inhibited calmodulin‐stimulated cyclic nucleotide phosphodiesterase activity. The same concentrations of these proteins, however, had no appreciable effect on the basal phosphodiesterase activity. The isolated G i α and βγ subunits of GTP‐binding proteins were potent inhibitors of the calmodulin‐stimulated phosphodiesterase activity, but G o α was very weak. Therefore, the βγ subunits were likely to be the major active molecules in the brain membranes. GTP‐binding proteins were shown to bind directly to calmodulin in a Ca 2+ ‐dependent manner by a gel permeation binding experiment.