Membrane association and conformational change of palmitoylated G(o)alpha.
Bovine brain G(o)alpha was specifically palmitoylated in vitro. The apparent dissociation constant for depalmitoylated G(o)alpha (dG(o)alpha) was 0.273 microM, while that for palmitoylated G(o)alpha (pG(o)alpha) was 5.77 nM. The dissociation rate constant (K(21)) and dissociation half-life for dG(o)alpha were 8.4x10(-4) min and 825 min respectively, while no significant dissociation of pG(o)alpha was detected. The limiting membrane insertion pressures for pG(o)alpha and dG(o)alpha were 44.4 mN/m and 41.3 mN/m respectively. These data suggested that palmitoylation facilitated the membrane association of G(o)alpha. Conformational changes of dG(o)alpha and pG(o)alpha detected by monitoring fluorescence spectra and fluorescence quenching were significantly different after they were associated with the membrane. It was suggested that conformational changes of G(o)alpha upon membrane association might be related to regulation of G(o)alpha signaling by palmitoylation.
Yang
S
S
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, PR China.
Zhang
L
L
Huang
Y
Y
D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020962:Heterotrimeric GTP-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation
D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020962:Heterotrimeric GTP-Binding Proteins; D003545:Cysteine