Phytochromes photoreceptors

In contrast to the other, morphologically relevant photoreceptor phytochrome, no unequivocal assay is available for the bluelight photoreceptor. This makes its purification and molecular characterization extremely difficult. 

Helfrich-Forster C, Winter C, Hofbauer A, Hall JC, Stanewsky R 2001 The circadian clock of fruit flies is blind after elimination of all known photoreceptors. Neuron 30 249-261 Lin FJ, Song W, Meyer-Bernstein E, Naidoo N, Sehgal A 2001 Photic signaling by cryptochrome in the Drosophilacitcidiaa system. Mol Cell Biol 21 7287-7294 Mas P, Devlin PF, Panda S, Kay SA 2000 Functional Interaction of phytochrome B and cryptochrome 2. Nature 408 207-211... 

Somers DE, Devlin PF, Kay SA 1998 Phytochromes and cryptochromes in the entrainment of th Arabidopsis circadian clock. Science 282 1488-1490 Stanewsky R, Kaneko M, Emery P et al 1998 The cryb mutation identifies cryptochrome as a circadian photoreceptor in Drosophila. Cell 95 681-692 Wang ZY, Tobin EM 1998 Constitutive expression of the CIRCADIAN CLOCK ASSOCIATED 1 CCAl gene disrupts circadian rhythms and suppresses its own expression. Cell 93 1207-1217... 

Davis, S.J. Vener, A.V. Vierstra, R.D. Bacteriophytochromes phytochrome-like photoreceptors from nonphotosynthetic eubacteria. Science, 286, 2517-2520 (1999)... 

One further problem is the large overshoot in ABA production in wilted leaves. With applied ABA a doubling of the ABA content of the leaf is usually adequate for stomatal closure, while increases up to 40-fold have been reported in wilted leaves. However, extractions of whole leaves do not take into account the location of ABA within the leaf. Perhaps much of the hormone is sequestered in a compartment that has no access to the guard cells. Thus, it would be of much importance to determine the distribution of ABA at the tissue level as well as its intracellular location. Since ABA is a small water-soluble molecule, conventional fractionation techniques may not be suitable to determine its distribution in various organelles. A highly specific immunological method for detection of ABA has recently been developed (38, 39). It is conceivable that this technique could be further developed for determining the cellular localization of ABA as has already been done for the photoreceptor phytochrome (77, 78). 

Our retina has red, green, and blue cones which include rhodopsins as photoreceptors [6-8], Phytochromes are photo-sensors of green plants [9], Biological luminescences from fireflies [10] and some jellyfishes [11] are also beautiful activities of living organism. Recently, fluorescent proteins are routinely applied as molecular markers for gene expression in the field of molecular biology [12]. 

Phytochromes are a family of bilin binding proteins that function as photoreceptors, regulating many physiologic processes... 

Light regulates many physiological processes other than photosynthesis in plants. The most important photoreceptor for such processes in higher plants is phytochrome. The article deals with recent results on chemical, biochemical, and biophysical characterization of isolated phytochrome. Furthermore recent investigations on phytochrome in the cell are summarized (including biosynthesis, destruction, and localization). The present view on possible primary... 

The most important photoreceptor for photomorphogenesis in higher plants is phytochrome which governs a multiplicity of photoresponses, some of which are summarized in Table 1. Photoresponses can be subdivided into irreversible photo-differentiations (attributable to differential activation of genes) and reversible photomodulations (most commonly attributed to membrane effects)111 198). Examples for both kinds of photoresponses governed by phytochrome are given in Table 1. 

Kamiol B, Wagner JR, Walker, JM, Vierstra RD (2005) Phylogenetic analysis of the phytochrome superfamily reveals distinct microbial subfamilies of photoreceptors. Biochem J 392 103-116... 

The photoreceptor molecules used by different microorganisms for light perception vary significantly and fall in different classes including BLUE proteins, cryptochromes, phototropins, phytochromes, and rhodopsins. Other prokaryotic and eukaryotic organisms use photoactive yellow proteins (PYP) which contain a 4-hydroxycinnamate chromophore (21)., chlorophylls, carotenoids, phycobilins, and pterins. Hypericins have been found to be involved in photoorientation of ciliates (22). 

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