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 (G(t)αβγ) available through sequestration of the βγ subunits (G(t)βγ). The structure of the phosphophosducin/G(t)βγ complex combined with mutational and biophysical analysis provides a stereochemical mechanism for the regulation of the phosducin-G(t)βγ 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 G(t)βγ, leading to the release of unencumbered G(t)βγ, which reassociates with the membrane and G(t)α to form a signaling-competent G(t)αβγ heterotrimer.
Original language | English (US) |
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Pages (from-to) | 649-660 |
Number of pages | 12 |
Journal | Molecular cell |
Volume | 3 |
Issue number | 5 |
DOIs | |
State | Published - 1999 |
Externally published | Yes |
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology