A Golgi-localized Hexose Transporter Is Involved in Heterotrimeric G Protein-mediated Early Development in Arabidopsis

Signal transduction involving heterotrimeric G proteins is universal among fungi, animals, and plants. In plants and fungi, the best understood function for the G protein complex is its modulation of cell proliferation and one of several important signals that are known to modulate the rate at which these cells proliferate is d-glucose. Arabidopsis thaliana seedlings lacking the β subunit (AGB1) of the G protein complex have altered cell division in the hypocotyl and are d-glucose hypersensitive. With the aim to discover new elements in G protein signaling, we screened for gain-of-function suppressors of altered cell proliferation during early development in the agb1-2 mutant background. One agb1-2-dependent suppressor, designated sgb1-1D for suppressor of G protein beta1 (agb1-2), restored to wild type the altered cell division in the hypocotyl and sugar hypersensitivity of the agb1-2 mutant. Consistent with AGB1 localization, SGB1 is found at the highest steady-state level in tissues with active cell division, and this level increases in hypocotyls when grown on d-glucose and sucrose. SGB1 is shown here to be a Golgi-localized hexose transporter and acts genetically with AGB1 in early seedling development

Touch induces ATP release in Arabidopsis roots that is modulated by the heterotrimeric G-protein complex

Amongst the many stimuli orienting the growth of plant roots, of critical importance are the touch signals generated as roots explore the mechanically complex soil environment. However, the molecular mechanisms behind these sensory events remain poorly defined. We report an impaired obstacle-avoiding response of roots in Arabidopsis lacking a heterotrimeric G protein. Obstacle avoidance may utilize a touch-induced release of ATP to the extracellular space. While sequential touch stimulation revealed a strong refractory period for ATP release in response to mechanostimulation in wild-type plants, the refractory period in mutants was attenuated, resulting in extracellular ATP accumulation. We propose that ATP acts as an extracellular signal released by mechanostimulation and that the G-protein complex is needed for fine-tuning this response

A Golgi-localized Hexose Transporter Is Involved in Heterotrimeric G Protein-mediated Early Development in

Signal transduction involving heterotrimeric G proteins is universal among fungi, animals, and plants. In plants and fungi, the best understood function for the G protein complex is its modulation of cell proliferation and one of several important signals that are known to modulate the rate at which these cells proliferate is D-glucose. Arabidopsis thaliana seedlings lacking the � subunit (AGB1) of the G protein complex have altered cell division in the hypocotyl and are D-glucose hypersensitive. With the aim to discover new elements in G protein signaling, we screened for gain-of-function suppressors of altered cell proliferation during early development in the agb1-2 mutant background. One agb1-2dependent suppressor, designated sgb1-1 D for suppressor of G protein beta1 (agb1-2), restored to wild type the altered cell division in the hypocotyl and sugar hypersensitivity of the agb1-2 mutant. Consistent with AGB1 localization, SGB1 is found at the highest steady-state level in tissues with active cell division, and this level increases in hypocotyls when grown on D-glucose and sucrose. SGB1 is shown here to be a Golgi-localized hexose transporter and acts genetically with AGB1 in early seedling development