Farnesylation of retinal transducin underlies its translocation during light adaptation

Hidetoshi Kassai, Atsu Aiba, Kazuki Nakao, Kenji Nakamura, Motoya Katsuki, Wei Hong Xiong, King Wai Yau, Hiroo Imai, Yoshinori Shichida, Yoshinori Satomi, Toshifumi Takao, Toshiyuki Okano, Yoshitaka Fukada

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


G proteins are posttranslationally modified by isoprenylation: either farnesylation or geranylgeranylation. The γ subunit of retinal transducin (Tα/Tβγ) is selectively farnesylated, and the farnesylation is required for light signaling mediated by transducin in rod cells. However, whether and how this selective isoprenylation regulates cellular functions remain poorly understood. Here we report that knockin mice expressing geranylgeranylated Tγ showed normal rod responses to dim flashes under dark-adapted conditions but exhibited impaired properties in light adaptation. Of note, geranylgeranylation of Tγ suppressed light-induced transition of Tβγ from membrane to cytosol, and also attenuated its light-dependent translocation from the outer segment to the inner region, an event contributing to retinal light adaptation. These results indicate that, while the farnesylation of transducin is interchangeable with the geranylgeranylation in terms of the light signaling, the selective farnesylation is important for visual sensitivity regulation by providing sufficient but not excessive membrane anchoring of Tβγ.

Original languageEnglish (US)
Pages (from-to)529-539
Number of pages11
Issue number4
StatePublished - Aug 18 2005

ASJC Scopus subject areas

  • General Neuroscience


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