Synaptic membrane G proteins are complexed with tubulin in situ.

Abstract

The G proteins G S and Gi1 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 adenyl 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 s alpha but not G i alpha 1, responded to the addition of tubulin with a stable activation of adenyl cyclase. Conversely, membranes from rat cerebral cortex, which contain both G s and G i 1, responded to exogenous tubulin with a stable inhibition of adenyl cyclase. Unlike C6 membranes, cerebral cortex membranes are richly endowed with tubulin, and antitubulin antibodies immunoprecipitated complexes of tubulin and G i 1 and G s from detergent extracts of these membranes. Nearly 90% of the G s alpha 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.

• Authors: K Yan, E Greene, F Belga, M M Rasenick
• Journal: Journal of neurochemistry (J Neurochem) Vol. 66 Issue 4 Pg. 1489-95 (Apr 1996) ISSN: 0022-3042 [Print] England
• PMID: 8627303 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Adenylyl Cyclase Inhibitors
• Affinity Labels
• Azides
• Tubulin
• Guanylyl Imidodiphosphate
• GTP gamma-4-azidoanilide
• Guanosine Triphosphate
• GTP-Binding Proteins

Topics

• Adenylyl Cyclase Inhibitors
• Affinity Labels
• Animals
• Azides
• Cerebral Cortex (metabolism)
• Chickens
• GTP-Binding Proteins (analysis, metabolism)
• Glioma
• Guanosine Triphosphate (analogs & derivatives)
• Guanylyl Imidodiphosphate (pharmacology)
• Rats
• Sheep
• Synaptic Membranes (chemistry, enzymology)
• Synaptosomes (chemistry, metabolism)
• Tubulin (metabolism, pharmacology)
• Tumor Cells, Cultured (chemistry, enzymology)