Regulation of Golgi structure through heterotrimeric G proteins

We have previously shown that ilimaquinone (IQ), a marine sponge metabolite, causes complete vesiculation of the Golgi stacks. By reconstituting the I-mediated vesiculation of the Golgi apparatus in permeabilized cells, we now demonstrate that this process does not require ARF and coatomers, which are necessary for the formation of Golgi-derived COPI vesicles. We find that IQ-mediated Golgi vesiculation is inhibited by G-alpha(s)-GDP and G-alpha(13)-GDP. Interestingly, adding beta-gamma subunits in the absence of IQ is sufficient to vesiculate Golgi stacks. Our findings reveal that I-mediated Golgi vesiculation occurs through activation of heterotrimeric G proteins and that it is the free beta-gamma, and not the activated alpha subunit, that triggers Golgi vesiculation.