| First Author | Belcastro M | Year | 2012 |
| Journal | Invest Ophthalmol Vis Sci | Volume | 53 |
| Issue | 6 | Pages | 3084-91 |
| PubMed ID | 22491418 | Mgi Jnum | J:196834 |
| Mgi Id | MGI:5489995 | Doi | 10.1167/iovs.11-8798 |
| Citation | Belcastro M, et al. (2012) Phosphorylation of phosducin accelerates rod recovery from transducin translocation. Invest Ophthalmol Vis Sci 53(6):3084-91 |
| abstractText | PURPOSE: In rods saturated by light, the G protein transducin undergoes translocation from the outer segment compartment, which results in the uncoupling of transducin from its innate receptor, rhodopsin. We measured the kinetics of recovery from this adaptive cellular response, while also investigating the role of phosducin, a phosphoprotein binding transducin betagamma subunits in its de-phosphorylated state, in regulating this process. METHODS: Mice were exposed to a moderate rod-saturating light triggering transducin translocation, and then allowed to recover in the dark while free running. The kinetics of the return of the transducin subunits to the outer segments were compared in transgenic mouse models expressing full-length phosducin, and phosducin lacking phosphorylation sites serine 54 and 71, using Western blot analysis of serial tangential sections of the retina. RESULTS: In mice expressing normal phosducin, transducin alpha and betagamma subunits returned to the outer segments with a half-time (t(1/2)) of approximately 24 and 29 minutes, respectively. In the phosducin phosphorylation mutants, the transducin alpha subunit moved four times slower, with t(1/2) approximately 95 minutes, while the movement of transducin betagamma was less affected. CONCLUSIONS: We demonstrate that the recovery of rod photoreceptors from the ambient saturating levels of illumination, in terms of the return of the light-dispersed transducin subunits to the rod outer segments, occurs six times faster than reported previously. Our data also support the notion that the accumulation of transducin alpha subunit in the outer segment is driven by its re-binding to the transducin betagamma dimer, because this process is accelerated significantly by phosducin phosphorylation. |
