Cryptochrome regulated

Folate and FAD are also components of cryptochromes, proteins widespread in living organisms. Cryptochromes are considered photolyase sequence homologues with no DNA repair activities but with blue light-activated factors. Cryptochromes regulate growth and development in plants and seem to be responsible for the synchronization of circadian rhythms in animals and human. ... 

Sancar, A., Regulation of the mammalian circadian clock by cryptochrome, J. Biol. Chem., 279, 34079, 2004. 

Partch, C. L. et al., Postranslational regulation of mammalian circadian clock by cryptochrome and proteinphosphatase 5, Proc Aarf Acad. Sci. USA, 103, 10467, 2006. Briggs, W.R., Christie, J.M., and Salomon, M., Phototropins a new family of flavinbinding blue light receptors in plants, Antioxid. Redox Signal, 3, 775, 2001. Briggs,W.R. et al.. The phototropin family of photoreceptors. Plant Cell, 13, 993, 2001. 

WADE, H.K., BIBIKOVA, T.N., VALENTINE, W.J., JENKINS, G.I., Interactions within a network of phytochrome, cryptochrome and UV-B phototransduction pathways regulate chalcone synthase gene expression in Arabidopsis leaf tissue, Plant J., 2001, 25, 675-685. 

Shalitin D, Yang H, Mockler TC et al 2002 Regulation of A rahidopsis cryptochrome 2 by blue-light-dependent phosphorylation. Nature 417 763—767 Stanewsky R, Kaneko M, Emery P et al 1998 The cryb mutation identifies cryptochrome as a circadian photoreceptor in Drosophila. Cell 95 681-692 Takahashi JS, DeCoursey PJ, Bauman L, Menaker M 1984 Spectral sensitivity of a novel photoreceptive system mediating entrainment of mammalian circadian rhythms. Nature 308 186-188... 

Vitatema MH, Selby CP, Todo T et al 1999 Differential regulation of mammalian period genes and circadian rhythmicity by cryptochromes 1 and 2. Proc Natl Acad Sci USA 96 12114—12119... 

Kay It is external coincidence. Both are required. If you activate phytochrome A (phjA) and cryptochrome 2 cry 2) in wild-type plants at the end of the day in short days this has no effect on flowering because the phase of CO expression is such that it is at too low a level. It really seems to be entrainment regulating CO waveform. This is where Bunning in the 1940s was brilliant in proposing how this could work. This story will get even prettier when we fulfil the prediction that this light is leading to some post-translational modulation of CO protein or potentially a CO partner. 

Emery P, So WV, Kaneko M, Hall JC, Rosbash M 1998 CRY, a Drosophila clock and light-regulated cryptochrome, is a major contributor to circadian rhythm resetting and photosensitivity. Cell 95 669-679... 

Redox reactions have been proposed to play a key role in light-responsive activities of cryptochromes [98, 99], blue-light photoreceptors in plants, animals, and bacteria with widespread functions ranging from the regulation of circadian rhythms of plants and animals [13] to the sensing of magnetic fields in a number of species... 

Cryptochrome/photolyase blue light photoreceptor family. The photoreceptors in this family are flavoproteins. They have a wide range of functions including circadian clock regulation, seed germination, and pigment accumulation. 

In contrast to the paucity of biochemical data on the photosensory functions of cryptochromes, there are extensive genetic and cell biology data on the roles of cryptochromes in blue light, photoreception in plants and animals, and circadian clock regulation in animals (Gashmore, 2003 Lin and Shalitin, 2003 Sancar, 2003). In Arabidopsis, blue light inhibits elongation of hypocotyls in a cryptochrome-dependent manner. In animals. 

T6th, R., Kevei, E., Hall, A., Millar, A.J., Nagy.E, and Kozma-Bogndr, L., Circadian clock-regulated expression of phytochrome and cryptochrome genes in Arabidopsis, Plant Physiol, 127,1607,2001. 

Guo, H. et al.. Regulation of flowering time hy Arabidopsis photoreceptors. Science, 279,1360,1998. Imaizumi, X, Kanegae, X, and Wada, M., Cryptochrome nucleocytoplasmatic distribution and gene expression are regulated by light quality in the fern Adiantum capillus-veneris. Plant Cell, 12, 81, 2000. 

---