Transmembrane signal transduction via heterotrimeric G proteins is reported to be inhibited by RGS (regulators of G-protein signalling) proteins. These RGS proteins work by increasing the GTPase activity of G protein alpha-subunits (G alpha), thereby driving G proteins into their inactive GDP-bound form. However, it is not known how RGS proteins regulate the kinetics of physiological responses that depend on G proteins. Here we report the isolation of a full-length complementary DNA encoding a neural-tissue-specific RGS protein, RGS8, and the determination of its function. We show that RGS8 binds preferentially to the alpha-subunits G(alpha)o and G(alpha)i3 and that it functions as a GTPase-activating protein (GAP). When co-expressed in Xenopus oocytes with a G-protein-coupled receptor and a G-protein-coupled inwardly rectifying K+ channel (GIRK1/2), RGS8 accelerated not only the turning off but also the turning on of the GIRK1/2 current upon receptor stimulation, without affecting the dose-response relationship. We conclude that RGS8 accelerates the modulation of G-protein-coupled channels and is not just a simple negative regulator. This property of RGS8 may be crucial for the rapid regulation of neuronal excitability upon stimulation of G-protein-coupled receptors.

We have constructed a one-inch-sized apparatus for gel electrophoresis (µGE). This apparatus was shown to be of high performance and to have potentials to apply to versatile purposes mainly due to its speed and economy. The temperature gradient gel electrophoresis as well as the conventional gel electrophoresis of multi-wells was successfully performed with both DNAs and proteins. Secondary gel electrophoreses in the two alternative modes, band-cut and zone-cut, were shown to be operable.