Constant domains diversity

RGS proteins (see Abramow-Newerly et al. 2006 De Vries et al. 2000 Druey 2001 Neitzel and Hepler 2006 Tinker 2006 Willars 2006 for reviews) comprise a wide and rather diverse family, with 30+ members, but with a common 120-residue RGS domain that enables binding to the G-protein a-subunit. The effect of this is to lower the energy requirement for GTP hydrolysis and hence to accelerate the GTPase activity of the a-subunit. This is reflected in the faster offset of Ga or Gpy-mediated effector responses noted above. Because the effective dissociation equilibrium constant for G-protein-effector interaction (Kdlss) is determined by l+ff/kon x G (where G is the concentration of activated G-protein), RGS-accelerated GTPase activity reduces effector response to agonist, effectively... 

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