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Synaptic Membrane G Proteins Are Complexed with Tubulin In Situ
Author(s) -
Yan Kun,
Greene Erin,
Belga Ferdinand,
Rasenick Mark M.
Publication year - 1996
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 - 10.1046/j.1471-4159.1996.66041489.x
Subject(s) - tubulin , adenylyl cyclase , g protein , cytoskeleton , cell cortex , microbiology and biotechnology , biology , gs alpha subunit , microtubule , gtp' , gtp binding protein regulators , biochemistry , signal transduction , cell , enzyme
The G proteins G s and G i1 appear to be capable of binding to tubulin specifically, and it has been suggested that such binding results in G protein activation via direct transfer of GTP. This study was undertaken to demonstrate that consequences of G protein activation by tubulin, i.e., stimulation or inhibition of adenylyl cyclase, were dependent on the G proteins expressed as well as unique aspects of the membrane or cytoskeleton in a given cell type. Membranes from rat C6 glioma cells, which express G sα but not G iα1 , responded to the addition of tubulin with a stable activation of adenylyl cyclase. Conversely, membranes from rat cerebral cortex, which contain both G s and G i1 , responded to exogenous tubulin with a stable inhibition of adenylyl cyclase. Unlike C6 membranes, cerebral cortex membranes are richly endowed with tubulin, and antitubulin antibodies immunoprecipitated complexes of tubulin and G i1 or G s from detergent extracts of these membranes. Nearly 90% of the G sα from Triton X‐114 extracts coimmunoprecipitated with tubulin, suggesting that these proteins exist as a complex in the synaptic membrane. Such complexes may provide the framework for a G protein‐cytoskeleton link that participates in the modulation of cellular signal transduction.