G protein activation is prerequisite for functional coupling between Galpha/Gbetagamma and tubulin/microtubules.
Heterotrimeric G proteins participate in signal transduction by transferring signals from cell surface receptors to intracellular effector molecules. Interestingly, recent results suggest that G proteins also interact with microtubules and participate in cell division and differentiation. It has been shown earlier that both alpha and betagamma subunits of G proteins modulate microtubule assembly in vitro. Since G protein activation and subsequent dissociation of alpha and betagamma subunits are necessary for G proteins to participate in signaling processes, here we asked if similar activation is required for modulation of microtubule assembly by G proteins. We reconstituted Galphabetagamma heterotrimer from myristoylated-Galpha and prenylated-Gbetagamma, and found that the heterotrimer blocks Gi1alpha activation of tubulin GTPase and inhibits the ability of Gbeta1gamma2 to promote in vitro microtubule assembly. Results suggest that G protein activation is required for functional coupling between Galpha/Gbetagamma and tubulin/microtubules, and supports the notion that regulation of microtubules is an integral component of G protein mediated signaling.
Roychowdhury
Sukla
S
Neurological and Metabolic Disorder, University of Texas, El Paso, TX 79968, USA. sukla@utep.edu
Martinez
Liliana
L
Salgado
Lucy
L
Das
Siddhartha
S
Rasenick
Mark M
MM
D000818:Animals; D001921:Brain / Q000378:metabolism; D044385:GTP-Binding Protein alpha Subunits / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D044387:GTP-Binding Protein beta Subunits / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D044388:GTP-Binding Protein gamma Subunits / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D020836:Protein Structure, Quaternary; D012756:Sheep; D014404:Tubulin / Q000378:metabolism*
C118981:G-protein Beta gamma; D044385:GTP-Binding Protein alpha Subunits; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D014404:Tubulin