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	Lem Laboratory
		A second objective of studies in the Lem lab are to investigate the role of transducin in retinal degenerative disease and phototransduction signaling mechanisms.
		Using a transducin knockout mouse produced in our lab, we are studying transducin mutants with defects in their ability to interact with a member of the family of RGS (regulator of G-protein signaling) proteins and the inhibitory PDE subunit.
		The transducin knockout mouse is also being used to test the ‘equivalent light hypothesis’, which proposes that some cases of RP cause retinal degeneration by mimicking continuous light exposure in the absence of light.
	www.tufts.edu /sackler/cmdb/lem-lab.htm (380 words)

	transducin \| English \| Dictionary & Translation by Babylon
		Transducin (also called Gt) is a heterotrimeric G protein that is naturally expressed in vertebrate retina rods and cones (a different Transducin gene is expressed in each cell type).
		Heterotrimeric Transducin (alpha-beta-gamma subunits) is activated by a conformational change in rhodopsin due to the adsorption of a photon by rhodopsin's active group retinal; Activation causes the GDP bound to the alpha subunit to be exchanged with GTP from solution and results in activated alpha dissociating from beta-gamma.
		The termination of Transducin activity occurs when (active) GTP bound Transducin is hydrolyzed to Transducin-GDP, a process which is accelerated by a complex containing an RGS (Regulator of G-protein signaling)-protein and the gamma-subunit of the effector, cyclic GMP Phosphodiesterase.
	www.babylon.com /definition/transducin (184 words)

	biophys_publ_Light-dependent transducin activation - Forschungszentrum Rossendorf
		The role of the Schiff base proton in photoactivation was investigated by measuring transducin activation as a function of photoactivation wavelength.
		The transducin activation action spectra of rhodopsin and of mutant E113Q were found to be very similar to their UV-visible absorption spectra.
		The findings are also consistent with transducin activation studies of mutant apoproteins regenerated with all-trans-retinal, or of mutant apoproteins alone, suggesting that the active state of rhodopsin can be formed via a number of pathways.
	www.fz-rossendorf.de /pls/rois/Cms?pOid=11718 (253 words)

	Transducin - Wikipedia, the free encyclopedia
		Transducin is activated by a conformational change in rhodopsin due to the adsorption of a photon by rhodopsin's active group retinal; active Transducin (also called G
		Decrease in cGMP concentration leads to the closure of cGMP-regulated ion channels and a hyperpolarized membrane potential.
		Shortly after the activation of cyclic GMP Phosphodiesterase, GTP bound Transducin (active) is hydrolyzed to GDP-Transducin and thereby inactivated by a RGS (Regulator of G-protein signaling)-protein.
	en.wikipedia.org /wiki/Transducin (133 words)

	Origin of Reproducibility in the Responses of Retinal Rods to Single Photons -- Rieke and Baylor 75 (4): 1836 -- ...
		This manipulation changed the rate of transducin activation by a factor of 5, as judged by the slope of the rising phase of the flash response.
		This relative insensitivity of the response kinetics to changes in the rate of transducin activation indicates that rhodopsin's catalytic lifetime is not regulated by a feedback originating at or downstream of active transducin.
		In the absence of GDP, the dissociation rate of rhodopsin-transducin is determined by the GTP concentration; lowering the GTP concentration slows dissociation of rhodopsin-transducin and thus slows the binding of kinase and arrestin.
	www.biophysj.org /cgi/content/full/75/4/1836 (9071 words)

	biophys_publ_Binding of transducin and transducin-derived peptides to rhodopsin studies by attenuated total ...
		Abstract: Fourier transform infrared difference spectroscopy combined with the attenuated total reflection technique allows the monitoring of the association of transducin with bovine photoreceptor membranes in the dark.
		AC-terminal peptide comprising amino acids 340-350 of the transducin alpha-subunit reproduces the frequencies and isotope sensitivities of several of the transducin-induced bands between 1500 and 1800 cm-1, whereas an N-terminal peptide (aa 8-23) does not.
		The 1735 cm-1 vibration is also seen in the complex with C-terminal peptides devoid of free carboxylic acid groups, indicating that the corresponding carbonyl group is located on rhodopsin.
	www.fz-rossendorf.de /pls/rois/Cms?pOid=11727 (258 words)

	Coupling of Human delta -Opioid Receptor to Retinal Rod Transducin in Chinese Hamster Ovary Cells -- Varga et al. 292 ...
		Nucleotide sequence alignment of the transducin cDNA fragment obtained from CHO cells with the appropriate fragment (from nucleotide 148 to nucleotide 465) of the mouse rod transducin cDNA.
		Transducin was previously thought to be expressed specifically in the retina and the pineal gland.
		Raport CJ, Dere B and Hurley JB (1989) Characterization of the mouse rod transducin alpha subunit gene.
	jpet.aspetjournals.org /cgi/content/full/292/1/209 (3813 words)

	Zhang, Mol Vis 2003; 9:231-237.
		We show that the redistribution of rod arrestin and transducin does not depend on one another and that phosphorylation of the receptor is not necessary for either rod or cone arrestin translocation.
		Transducin, the heterotrimeric G protein of the rod phototransduction cascade, is activated by interacting with R*.
		Diurnal expression of transducin mRNA and translocation of transducin in rods of rat retina.
	www.molvis.org /molvis/v9/a34 (3877 words)

	Retina International's Scientific Newsletter - Transducin
		Transducin is a heterotrimer made from a catalytic alpha subunit (GNAT) and an inhibitory beta-gamma-dimer (GNB-GNG) providing the first step of signal amplification in the visual cascade.
		Gerber,S., Rozet,J.M., Bonneau,D., Souied,E., Weissenbach,J., Frezal,J., Munnich,A., and Kaplan,J. Exclusion of the cone-specific alpha-subunit of the transducin gene in Stargardt's disease.
		Makino,E.R., Handy,J.W., Li,T., and Arshavsky,V.Y. The GTPase activating factor for transducin in rod photoreceptors is the complex between RGS9 and type 5 G protein beta subunit.
	www.retina-international.org /sci-news/gnt.htm (468 words)

	NEUROBIOLOGY: ON RETINA-CORTEX WIRING
		Transducin can accomplish this task itself by converting --hydrolyzing -- its bound GTP molecule into guanosine diphosphate, GDP.
		In this molecular cascade, then, the conversion of GTP to GDP by transducin is the rate-limiting step that defines the amount of time for which a photoreceptor responds to a light pulse.
		In contrast, the hydrolysis of GTP by transducin requires tens of seconds to complete, making it difficult to understand how such a mechanism could account for the rapid turn-off of photoreceptor cells.
	www.scienceweek.com /2004/sa040924-1.htm (1652 words)

	Binding of Transducin and Transducin-Derived Peptides to Rhodopsin Studied by Attenuated Total Reflection-Fourier ...
		Rhodopsin-stimulated activation-deactivation cycle of transducin: kinetics of the intrinsic fluorescence response of the
		Structural changes in the peptide backbone in complex formation between activated rhodopsin and transducin studied by FTIR spectroscopy.
		The intrinsic fluorescence of the alpha subunit of transducin.
	www.biophysj.org /cgi/content/full/75/3/1306 (6654 words)

	Protein regulation study at Yale confirms suspicions on how hereditary blindness occurs
		It has been known for some time that a visual protein called transducin activates a downstream protein called phosphodiesterase in the signal transduction pathway.
		The system had to develop a way in which transducin could be effectively turned off as soon as it activated phosphodiesterase, and not before.
		Transducin, Slep said, is just one of many G-proteins in the human body.
	www.eurekalert.org /pub_releases/2001-03/YU-Prsa-2603101.php (559 words)

	MDA Laboratories, The Visual Cascade
		This pathway begins when rhodopsin (R), a 7 pass domain membrane-bound protein in rod photoreceptor cells, is activated by light.
		The subsequent decrease of cGMP concentration closes the cGMP-gated channels on the photoreceptor cells, causing a shift in the cell's electric potential and a subsequent neural impulse to the brain.
		The light-activated hydrolysis of cyclic GMP is shown schematically, with amplification of the photon signal illustrated by circular paths depicted by the arrows.
	www.eyesightresearch.org /visual_cascade.htm (219 words)

	Nicolet Application - ACCURA 100 DSO in medical research (Site not responding. Last check: 2007-10-18)
		Transducin is a protein in the eye that converts light into a nerve signal.
		A mixture of rhodospin and transducin is placed between lenses (1) of an optical test setup.
		The rhodospin is activated by the light and will react with the transducin.
	www.nicolet.nl /appMedical.html (435 words)

	Darwinism Refuted.com
		When it connects with rhodopsin, transducin releases the GDP molecule and is linked to a new molecule called GTP.
		As soon as this chain reaction is completed, other specialized proteins within the cells convert elements such as 11-cis-retinal, rhodopsin and transducin back to their original states.
		The eye is under a constant shower of photons, and the chain reactions within the eye's sensitive cells enable it to perceive each one of these.
	www.darwinismrefuted.com /irreducible_complexity_04.html (912 words)

	Glossary: INFERRING THE RETINAL ANATOMY AND VISUAL CAPACITIES OF EXTINCT VERTEBRATES
		In vertebrates, activated transducin catalyzes the activation of a phosphodiesterase.
		This change in the voltage across the cell membrane results in a decrease in the rate at which neurotransmitter molecules are released at the base of the cell.
		Since the absorption of one photon can cause the opsin to convert many transducin molecules to their active form, and each activated transducin molecule can convert the activation of many phosphodiesterase molecules, and each phosphodiesterase molecule can isomerize many cGMP molecules, photon absorption is said to be amplified by the phototransduction process.
	www.nhm.ac.uk /hosted_sites/pe/2000_1/retinal/gloss.htm (2152 words)

	WHAT ARE THE MECHANISMS OF PHOTORECEPTOR ADAPTATION?
		It is important to point out that the majority of biochemical studies have used very unphysiological conditions: diluted suspensions of disrupted ROS (or purified enzymes) and illumination bleaching a substantial fraction of the rhodopsin present.
		Gray-Keller, M.P., Biernbaum, M.S. and Bownds, M.D. (1990) Transducin activation in electropermeabilized frog rod outer segments is highly amplified, and a portion equivalent to phosphodiesterase remains membrane-bound.
		Neubert, T.A., Johnson,R.S., Hurley,J.B. and Walsh,K.A. (1992) The rod transducin alpha subunit amino terminus is heterogeneously fatty acylated.
	www.bbsonline.org /documents/a/00/00/04/35/bbs00000435-00/bbs.neur3.bownds.html (11479 words)

	Gao, Mol Vis 1998; 4:16.
		Cone and rod transducins are both heterotrimeric G proteins consisting of single [alpha]-, ß- and [gamma]-subunits.
		Functionally, however, the two transducins have the same role in the visual response of their corresponding photoreceptors.
		In both cases the transducin protein is separated into an [alpha]-subunit and a ß/[gamma]-subunit complex after interaction with light activated opsin.
	www.molvis.org /molvis/v4/a16 (2886 words)

	Retina International's Scientific Newsletter - Transducin Mutations
		Dryja, T.P., Hahn, L.B., Reboul, T., and Arnaud, B. Missense mutation in the gene encoding the alpha subunit of rod transducin in the Nougaret form of congenital stationary night blindness.
		Gao, Y.Q., Danciger, M., Akhmedov, N.B., Zhao, D.Y., Heckenlively, J.R., Fishman, G.A., Weleber, R.G., Jacobson, S.G., and Farber, D.B. Exon screening of the genes encoding the beta- and gamma-subunits of cone transducin in patients with inherited retinal disease.
		Magovcevic, I., Weremowicz, S., Morton, C.C., Fong, S.L., Berson, E.L., and Dryja, T.P. Mapping of the human cone transducin alpha-subunit (GNAT2) gene to 1p13 and negative mutation analysis in patients with Stargardt disease.
	www.retina-international.org /sci-news/gntmut.htm (130 words)

	Rods and cones (Site not responding. Last check: 2007-10-18)
		Transducin is one of many G-proteins, which are discussed in Sci.
		This effect of R* on transducin would be a serial activation, one transducin after another.
		It also appears that it is a metastable state, metarhodopsin II, that is responsible for the release-and-activation of transducin, and that this state lasts about 10 msec; therefore the rate of activation could be seen as 50000/sec.
	www.engin.brown.edu /courses/en122/Lcturs/PhotoTrans.htm (1631 words)

	The Rockefeller University - Heads of Laboratories
		The active GTP-bound form of transducin then dissociates from the receptor and carries the signal to the next component of the biochemical visual cascade, cyclic-GMP phosphodiesterase.
		Flash photolysis studies of site-directed rhodopsin mutants previously showed that at least the second and third cytoplasmic loops of rhodopsin are involved in activation of transducin.
		We recently succeeded in reconstituting recombinant transducin expressed in Sf9 insect cells with purified rhodopsin and phosphodiesterase.
	www.rockefeller.edu /research/abstract.php?id=94 (767 words)

	Design in Nature Demands a Designer, Let's Take a Look at the Chemistry of Sight - Dandy Designs - Does God Exist? - ...
		Inactivated Transducin is bound to a small molecule known as GDP.
		When Transducin is activated by the change in shape of Rhodopsin, the GDP is chemically changed into GTP.
		Activated Transducin in turn activates an enzyme known as Cyclic GMP Phosphodiesterase.
	www.doesgodexist.org /JanFeb02/DesignInNatureDemandsADesignerLetsTakeALookAtTheChemistryOfSight.html (1044 words)

	Developmental Expression Pattern of Phototransduction Components in Mammalian Pineal Implies a Light-Sensing Function ...
		Mouse rod transducin is used as a probe.
		Raport CJ, Dere B, Hurley JB (1989) Characterization of the mouse rod transducin alpha-subunit gene.
		Spessert R (1993) Vasoactive intestinal peptide stimulation of cyclic guanosine monophosphate formation: further evidence for a role of nitric oxide synthase and cytosolic guanylate cyclase in rat pinealocytes.
	www.jneurosci.org /cgi/content/full/17/21/8074 (5515 words)

	Tramadol, buy tramadol, antibiotics, Weight Loss drugs, weight loss herbs, weight loss herbal formula, weight loss, ... (Site not responding. Last check: 2007-10-18)
		Retinal photoreceptors use the heterotrimeric G protein transducin to couple rhodopsin to a biochemical cascade that underlies the electrical photoresponse.
		Although rods and cones seem to contain distinct transducin subunits, it is not known whether phototransduction in a given cell type depends strictly on a single form of each subunit.
		In hemizygous knockout mice, there was a small reduction in retinal transducin alpha-subunit content but retinal morphology and the physiology of single rods were largely normal.
	www.viagenbio.com /ref-transgenic/transgenic-research-abs5.32.html (1181 words)

	Discovery Institute - Article Database - Evidence for Intelligent Design from Biochemistry
		The change in the shape of retinal forces a change in the shape of the protein, rhodopsin, to which the retinal is tightly bound.
		Before bumping into activated rhodopsin, transducin had tightly bound a small molecule called GDP.
		But when transducin interacts with activated rhodopsin, the GDP falls off and a molecule called GTP binds to transducin.
	www.discovery.org /scripts/viewDB/index.php?command=view&id=51&program=Technology (4054 words)

	A cyclic–nucleotide–suppressible conductance activated by transducin in taste cells
		We have shown that rod transducin is present in mammalian taste receptor cells, where it is activated by a bitter receptor and in turn activates a phosphodiesterase
		Here we introduce into frog taste cells peptides derived from transducin's phosphodiesterase–interaction region, which cause an inward whole–cell current in a subset of cells.
		We propose that transducin, via phosphodiesterase, decreases cyclic nucleotide levels to activate the cyclic-nucleotide-suppressible conductance, leading to Ca influx and taste-cell depolarization.
	www.nature.com /doifinder/10.1038/376085a0 (431 words)

	CORRELATION OF PHENOTYPE WITH GENOTYPE
		While transducin is bound to rhodopsin, the `-subunit of the G-protein exchanges a bound GDP for GTP.
		The `-subunit of transducin with bound GTP dissociates from the ~- and k- subunits so that it can bind to one of the two inhibitory k-subunits of phosphodiesterase.
		Therefore, although many of the proteins (and their genes) involved in phototransduction are well characterized, there are certain to be other genes and proteins involved that are not known yet.
	bbsonline.cup.cam.ac.uk /Preprints/OldArchive/bbs.neur3.daiger.html (12151 words)

	THE MOLECULAR BASIS OF RETINAL DEGENERATION
		The transducin alpha dissociates from transducin beta-gamma complex.
		The transducin alpha binds to gamma subunit of cGMP-phosphodiesterase (PDE).
		This interaction relieves the inhibitory effect of the gamma subunit on the catalytic alpha and beta subunits of PDE and allows the hydrolytic activity of these subunits to be increased almost 300 fold.
	www.bioscience.org /news/scientis/eye.htm (723 words)

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