京都大学 · 神経科学
Takahiro Yamashita教授の研究室は、光受容体たるオプシンの分子機構とその機能多様性を解明することを目的としています。特に、非視覚的光受容(視覚以外の生理的反応誘導)に関与するオプシン(Opn5、TMTオプシン、ピンオプシンなど)の光感受性、Gタンパク質選択性、および二重安定型色素としての性質に注目し、分子生物学的・生化学的アプローチを用いてその機能を解明しています。また、脊椎動物におけるオプシンの進化的多様性と機能分化のメカニズムについても、比較的種の広い系統を用いて研究を進めています。
Figures are computed from collected data and may differ slightly.
Opn5 (neuropsin) belongs to an independent group separated from the other six groups in the phylogenetic tree of opsins, for which little information of absorption characteristics and molecular properties of the members is available. Here we show that the chicken Opn5 (cOpn5m) is a UV-sensitive bistable pigment that couples with Gi subtype of G protein. The recombinant expression of cOpn5m in HEK 293s cells followed by the addition of 11- cis - and all-trans -retinal produced UV light-absorbing
Opn5 is one of the recently identified opsin groups that is responsible for nonvisual photoreception in animals. We previously showed that a chicken homolog of mammalian Opn5 (Opn5m) is a Gi-coupled UV sensor having molecular properties typical of bistable pigments. Here we demonstrated that mammalian Opn5m evolved to be a more specialized photosensor by losing one of the characteristics of bistable pigments, direct binding of all-trans-retinal. We first confirmed that Opn5m proteins in zebrafis
In contrast to the extensive studies of light-induced conformational changes in rhodopsin, the cytoplasmic architecture of rhodopsin related to the G protein activation and the selective recognition of G protein subtype is still unclear. Here, we prepared a set of bovine rhodopsin mutants whose cytoplasmic loops were replaced by those of other ligand-binding receptors, and we compared their ability for G protein activation in order to obtain a clue to the roles of the second and third cytoplasmi
Opsin family genes encode G protein-coupled seven-transmembrane proteins that bind a retinaldehyde chromophore in photoreception. Here, we sought potential as yet undescribed avian retinal photoreceptors, focusing on Opsin 3 homologs in the chicken. We found two Opsin 3-related genes in the chicken genome: one corresponding to encephalopsin/panopsin (Opn3) in mammals, and the other belonging to the teleost multiple tissue opsin (TMT) 2 group. Bioluminescence imaging and G protein activation assa
HLA-G allelic abnormality seemed to have little, if any, implication in the pathogenesis of habitual abortion.
Pinopsin is the opsin most closely related to vertebrate visual pigments on the phylogenetic tree. This opsin has been discovered among many vertebrates, except mammals and teleosts, and was thought to exclusively function in their brain for extraocular photoreception. Here, we show the possibility that pinopsin also contributes to scotopic vision in some vertebrate species. Pinopsin is distributed in the retina of non-teleost fishes and frogs, especially in their rod photoreceptor cells, in add
For pregnant women at a high risk of massive hemorrhage, our PAD program was safe and effective for avoiding allogeneic blood transfusion.
G protein-coupled receptors identified so far are classified into at least three major families based on their amino acid sequences. For the family of receptors homologous to rhodopsin (family 1), the G protein activation mechanism has been investigated in detail, but much less for the receptors of other families. To functionally compare the G protein activation mechanism between rhodopsin and metabotropic glutamate receptor (mGluR), which belong to distinct families, we prepared a set of bovine
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