Download MendeleyA molecular mechanism for the phosphorylation-dependent regulation of heterotrimeric G proteins by phosducin.
Gaudet, R., Savage, J.R., McLaughlin, J.N., Willardson, B.M., Sigler, P.B.(1999) Mol Cell 3: 649-660
- PubMed: 10360181
- DOI: https://doi.org/10.1016/s1097-2765(00)80358-5
- Primary Citation of Related Structures:
1B9X, 1B9Y - PubMed Abstract:
Visual signal transduction is a nearly noise-free process that is exquisitely well regulated over a wide dynamic range of light intensity. A key component in dark/light adaptation is phosducin, a phosphorylatable protein that modulates the amount of transducin heterotrimer (Gt alpha beta gamma) available through sequestration of the beta gamma subunits (Gt beta gamma). The structure of the phosphophosducin/Gt beta gamma complex combined with mutational and biophysical analysis provides a stereochemical mechanism for the regulation of the phosducin-Gt beta gamma interaction. Phosphorylation of serine 73 causes an order-to-disorder transition of a 20-residue stretch, including the phosphorylation site, by disrupting a helix-capping motif. This transition disrupts phosducin's interface with Gt beta gamma, leading to the release of unencumbered Gt beta gamma, which reassociates with the membrane and Gt alpha to form a signaling-competent Gt alpha beta gamma heterotrimer.
Organizational Affiliation:
Department of Molecular Biophysics, Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06511, USA.
