| First Author | Dexter PM | Year | 2018 |
| Journal | eNeuro | Volume | 5 |
| Issue | 3 | PubMed ID | 29911170 |
| Mgi Jnum | J:273962 | Mgi Id | MGI:6281242 |
| Doi | 10.1523/ENEURO.0144-18.2018 | Citation | Dexter PM, et al. (2018) Transducin beta-Subunit Can Interact with Multiple G-Protein gamma-Subunits to Enable Light Detection by Rod Photoreceptors. eNeuro 5(3):ENEURO.0144-18.2018 |
| abstractText | The heterotrimeric G-protein transducin mediates visual signaling in vertebrate photoreceptor cells. Many aspects of the function of transducin were learned from knock-out mice lacking its individual subunits. Of particular interest is the knockout of its rod-specific gamma-subunit (Ggamma1). Two studies using independently generated mice documented that this knockout results in a considerable >60-fold reduction in the light sensitivity of affected rods, but provided different interpretations of how the remaining alpha-subunit (Galphat) mediates phototransduction without its cognate Gbeta1gamma1-subunit partner. One study found that the light sensitivity reduction matched a corresponding reduction in Galphat content in the light-sensing rod outer segments and proposed that Galphat activation is supported by remaining Gbeta1 associating with other Ggamma subunits naturally expressed in photoreceptors. In contrast, the second study reported the same light sensitivity loss but a much lower, only approximately sixfold, reduction of Galphat and proposed that the light responses of these rods do not require Gbetagamma at all. To resolve this controversy and elucidate the mechanism driving visual signaling in Ggamma1 knock-out rods, we analyzed both mouse lines side by side. We first determined that the outer segments of both mice have identical Galphat content, which is reduced approximately 65-fold from the wild-type (WT) level. We further demonstrated that the remaining Gbeta1 is present in a complex with endogenous Ggamma2 and Ggamma3 subunits and that these complexes exist in wild-type rods as well. Together, these results argue against the idea that Galphat alone supports light responses of Ggamma1 knock-out rods and suggest that Gbeta1gamma1 is not unique in its ability to mediate vertebrate phototransduction. |
