REGULATION OF GOLGI STRUCTURE THROUGH HETEROTRIMERIC G-PROTEINS

We have previously shown that ilimaquinone (IQ), a marine sponge metab olite, causes complete vesiculation of the Golgi stacks. By reconstitu ting the I-mediated vesiculation of the Golgi apparatus in permeabiliz ed cells, we now demonstrate that this process does not require ARF an d coatomers, which are necessary for the formation of Golgi-derived CO PI vesicles. We find that IQ-mediated Golgi vesiculation is inhibited by G-alpha(s)-GDP and G-alpha(13)-GDP. Interestingly, adding beta-gamm a subunits in the absence of IQ is sufficient to vesiculate Golgi stac ks. Our findings reveal that I-mediated Golgi vesiculation occurs thro ugh activation of heterotrimeric G proteins and that it is the free be ta-gamma, and not the activated alpha subunit, that triggers Golgi ves iculation.