| First Author | Mao W | Year | 2013 |
| Journal | J Biol Chem | Volume | 288 |
| Issue | 8 | Pages | 5257-67 |
| PubMed ID | 23288843 | Mgi Jnum | J:196005 |
| Mgi Id | MGI:5486395 | Doi | 10.1074/jbc.M112.430058 |
| Citation | Mao W, et al. (2013) Functional comparison of rod and cone Galpha(t) on the regulation of light sensitivity. J Biol Chem 288(8):5257-67 |
| abstractText | The signaling cascades mediated by G protein-coupled receptors (GPCRs) exhibit a wide spectrum of spatial and temporal response properties to fulfill diverse physiological demands. However, the mechanisms that shape the signaling response of the GPCR are not well understood. In this study, we replaced cone transducin alpha (cTalpha) for rod transducin alpha (rTalpha) in rod photoreceptors of transgenic mice, which also express S opsin, to evaluate the role of Galpha subtype on signal amplification from different GPCRs in the same cell; such analysis may explain functional differences between retinal rod and cone photoreceptors. We showed that ectopically expressed cTalpha 1) forms a heterotrimeric complex with rod Gbeta(1)gamma(1), 2) substitutes equally for rTalpha in generating photoresponses initiated by either rhodopsin or S-cone opsin, and 3) exhibited similar light-activated translocation as endogenous rTalpha in rods and endogenous cTalpha in cones. Thus, rTalpha and cTalpha appear functionally interchangeable. Interestingly, light sensitivity appeared to correlate with the concentration of cTalpha when expression is reduced below 35% of normal. However, quantification of endogenous cTalpha concentration in cones showed a higher level to rTalpha in rods. Thus, reduced sensitivity in cones cannot be explained by reduced coupling efficiency between the GPCR and G protein or a lower concentration of G protein in cones versus rods. |
