a non-mammalian type opsin 5 functions dually in the photoreceptive and non-photoreceptive organs of birds一种非哺乳类视蛋白5功能会在感光和non-photoreceptive器官的鸟类.pdfVIP

A Non-Mammalian Type Opsin 5 Functions Dually in the Photoreceptive and Non-Photoreceptive Organs of Birds 1 2 1 2 2 Hideyo Ohuchi *, Takahiro Yamashita , Sayuri Tomonari , Sari Fujita-Yanagibayashi , Kazumi Sakai , Sumihare Noji1, Yoshinori Shichida2 1 Department of Life Systems, Institute of Technology and Science, University of Tokushima Graduate School, Tokushima, Japan, 2 Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan Abstract A mammalian type opsin 5 (neuropsin) is a recently identified ultraviolet (UV)-sensitive pigment of the retina and other photosensitive organs in birds. Two other opsin 5-related molecules have been found in the genomes of non-mammalian vertebrates. However, their functions have not been examined as yet. Here, we identify the molecular properties of a second avian opsin 5, cOpn5L2 (chicken opsin 5-like 2), and its localization in the post-hatch chicken. Spectrophotometric analysis and radionucleotide-binding assay have revealed that cOpn5L2 is a UV-sensitive bistable pigment that couples with the Gi subtype of guanine nucleotide-binding protein (G protein). As a bistable pigment, it also shows the direct binding ability to agonist all-trans-retinal to activate G protein. The absorption maxima of UV-light-absorbing and visible light-absorbing forms were 350 and 521 nm, respectively. Expression analysis showed relatively high expression of cOpn5L2 mRNA in the adrenal gland, which is not photoreceptive but an endocrine organ, while lower expression was found in the brain and retina. At the protein level, cOpn5L2 immunoreactive cells were present in the chromaffin cells of the adrenal gland. In the brain, cOpn5L2 immunoreactive cells were found in the parave