Xem 1-20 trên 21 kết quả Photoreceptor
  • Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Minireview cung cấp cho các bạn kiến thức về ngành y đề tài: The phytochrome red/far-red photoreceptor superfamily...

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  • Protein phosphatase 2A plays an important role in balancing phosphoryla-tion signals that are critical for cell proliferation and differentiation. Here, we report thatPpp2r5c(regulatory subunit of protein phosphatase 2A) expression was regulated by the transcription factor neural retina leucine-zipper (Nrl) through enhancement of its transcriptional activity on the Ppp2r5cpromoter.

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  • cilia are involved in diverse cellular functions, such as patterning of left-right asymmetry (nodal cilia), limb development, bone morphogenesis, and neurosensory functions (mechanosensation, olfaction, and photoreception). Cilia are also implicated in several developmental cascades, such as Wnt signaling, sonic hedgehog signaling, and platelet derived growth factor receptor signaling pathways.

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  • We normally think of the eye as an organ for vision, but due to the discovery of additional nerve connections from recently-detected novel photoreceptor cells in the eye to the brain, it is now understood how light also mediates and controls a large number of biochemical processes in the human body. The most important findings are related to the control of the biological clock and to the regulation of some important hormones through regular light-dark rhythms. This in turn means that lighting has a large influence on health, well-being and alertness.

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  • The physical basis of color exists in the interaction of light with matter, both outside and inside the eye. The sensation of color depends on physiological activity in the visual system that begins with the absorption of light in photoreceptors located in the retina of the eye and ends with patterns of biochemical activity in the brain. Perceived color can be described by the color names white, gray, black, yellow, orange, brown, red, green, blue, purple, and pink. These 11 basic color terms have unambiguous referents in all fully developed languages.

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  • Most information about the external world enters the human mind via the visual system; when seeing and looking are impaired, important aspects of life may elude us or the world becomes disturbingly distorted. While the globe may be likened to a camera, it is the brain that constructs an image of the world. It does this by making sense of the signals it receives from the retina, in which it is helped by data stored in memory as well as data gathered through other modes of perception.

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  • Tảo: Giải phẫu học, sinh hóa, và công nghệ sinh học Trên Assumption Đó photoreceptor IS không thể tách rời sự hiện diện của protein tiếp nhận ánh sáng nhưng không hẳn từ sự hiện diện của đốm mắt An, tiếp nhận ánh sáng hệ thống nhóm Chúng tôi sẽ vào ba loại chính. Cũng bao gồm các mô tả sẽ tảo Những người có mục đích Tài liệu cũng chỉ tiếp nhận ánh sáng đốm mắt khoán nội địa hóa. ...

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  • Retinal photoreceptor phosphodiesterase (PDE6), a key enzyme for photo-transduction, consists of a catalytic subunit complex (Pab) and two inhibi-tory subunits (Pcs). Pabhas two noncatalytic cGMP-binding sites. Here, using bovine PDE preparations, we show the role of these cGMP-binding sites in PDE regulation.

    pdf19p cosis54 05-01-2013 18 3   Download

  • Mutations in the human Crumbs homologue 1 (CRB1) gene are a frequent cause of various forms of retinitis pigmentosa. The CRB1–membrane-asso-ciated palmitoylated protein (MPP)5 protein complex is thought to organ-ize an intracellular protein scaffold in the retina that is involved in maintenance of photoreceptor–Mu¨ller glia cell adhesion.

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  • Thepcd1mutant of pea lacks heme oxygenase (HO) activity required for the synthesis of the phytochrome chromophore and is consequently severely deficient in all responses mediated by the phytochrome family of plant photoreceptors. Here we describe the isolation of the gene encoding pea heme oxygenase 1 (PsHO1) and confirm the presence of a mutation in this gene in the pcd1 mutant.

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  • The cones function under daylight (photopic) conditions. The cone system is specialized for color perception and high spatial resolution. The majority of cones are located within the macula, the portion of the retina serving the central 10° of vision. In the middle of the macula a small pit termed the fovea, packed exclusively with cones, provides best visual acuity. Photoreceptors hyperpolarize in response to light, activating bipolar, amacrine, and horizontal cells in the inner nuclear layer. ...

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  • Cone photoreceptors have faster light responses than rods and a higher demand for 11-cisretinal (11cRAL), the chromophore of visual pigments. RPE65 is the isomerohydrolase in the retinal pigment epithelium (RPE) that converts all-transretinyl ester to 11-cisretinol, a key step in the visual cycle for regenerating 11cRAL.

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  • The visual photoreceptor rhodopsin undergoes a series of conformational changes upon light activation, eventually leading to the active metarhodop-sin II conformation, which is able to bind and activate the G-protein, transducin.

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  • Bacterial phytochromes (Bphs) are ancestors of the well characterized plant photoreceptors. Whereas plant phyto-chromes perform their photoisomerization exclusively via a covalently bound bilin chromophore, Bphs are variable in their chromophore selection. This is demonstrated in the cyanobacterium CalothrixPCC7601 that expresses two Bphs, CphA and CphB. CphA binds phycocyanobilin (PCB) covalently, whereas CphB, lacking the covalently binding cysteine of the plant phytochromes, carries biliver-din IXa (BV) as the chromophore....

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  • The retinal pigment epithelium (RPE) is essential for main-tenance of photoreceptors and normally functions under conditions enriched with reactive oxygen species. RPE therefore expresses various defense enzymes against oxida-tive stress, including heme oxygenase-1 (HO-1). HO-1 catalyzes heme breakdown to release iron, carbon monox-ide, and biliverdin, which is reduced to bilirubin, a potent radical scavenger. HO-1 expression is induced by various environmental factors, which has been established as a def-ense mechanism....

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  • Guanylate cyclase-activating proteins (GCAPs) are neur-onal calcium sensors that activate membrane bound guanylate cyclases (EC 4.6.1.2.) of vertebrate photoreceptor cells when cytoplasmic Ca 2+ decreases during illumination. GCAPs contain fourEF-handCa 2+ -bindingmotifs, but the first EF-hand is nonfunctional. It was concluded that for GCAP-2, the loss of Ca 2+ -binding ability of EF-hand 1 resulted in a region that is crucial for targeting guanylate cyclase [Ermilov,A.N.,Olshevskaya, E.V.&Dizhoor,A.M. (2001) J. Biol. Chem.276, 48143–48148].

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  • Phytochromes are photoreceptor proteins that monitor the light environ-ment and regulate a variety of photomorphogenic responses to optimize the growth and development of plants. Phytochromes comprise N-terminal photosensory and C-terminal regulatory domains. They are mutually pho-toconvertible between a red-light-absorbing (Pr) and a far-red-light-absorb-ing (Pfr) form. Their interconversion by light stimuli initiates downstream signaling cascades.

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  • Thea-phycoerythrocyanin subunits of the different phy-coerythrocyanin complexes of the phycobilisomes from the cyanobacterium Mastigocladus laminosusperform a remarkable photochemistry. Similar to phytochromes – the photoreceptors of higher plants – the spectral pro-perties of the molecule reversibly change according to the irradiation wavelength. To enable extensive analyses,the protein has been produced at high yield by improving purification protocols.

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  • Cryptochromes are blue-light photoreceptors sharing sequence similarity to photolyases, a class of flavoenzymes catalyzing repair ofUV-damagedDNAvia electron transfer mechanisms. Despite significant amino acid sequence simi-larity in both catalytic and cofactor-binding domains, cryptochromes lack DNA repair functions associated with photolyases, and the molecular mechanism involved in cryptochrome signaling remains obscure.

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  • Arrestin is one of the key proteins for the termination of G protein signaling. ActivatedG protein-coupled receptors (GPCRs) are specifically phosphorylatedby G protein-coupledreceptor kinases (GRKs) and then bindto arrestins to preclude the receptor/G protein interaction, resulting in quenching of the following signal transduction. Vertebrates possess two types of arrestin; visual arrestin expressed exclusively in photoreceptor cells in retinae andpineal organs, andb-arrestin, which is expressedubiquitously....

    pdf7p tumor12 22-04-2013 11 1   Download

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