Membrane association and conformational change of palmitoylated G(o)alpha

Bovine brain G(0)alpha was specifically palmitoylated in vibro. The apparen t dissociation constant for depalmitoylated G(0)alpha (dG(0)alpha) was 0.27 3 muM, while that for palmitoylated G(0)alpha (pG(0)alpha) was 5.77 nM. The dissociation rate constant (K-21) and dissociation half-life for dG(0)alph a were 8.4 x 10(-4) min and 825 min respectively, while no significant diss ociation of pG(0)alpha was detected. The Limiting membrane insertion pressu res for pC,a and dG(0)alpha were 44.4 mN/m and 41.3 mN/m respectively. Thes e data suggested that palmitoylation facilitated the membrane association o f G(0)alpha. Conformational changes of dG(0)alpha and pG(0)alpha detected b y monitoring fluorescence spectra and fluorescence quenching were significa ntly different after they were associated with the membrane. It mas suggest ed that conformational changes of G(0)alpha upon membrane association might be related to regulation of G(0)alpha signaling by palmitoylation, (C) 200 1 Federation of European Biochemical Societies. Published by Elsevier Scien ce B,V, All rights reserved.