Cryptochromes are highly conserved molecules (evolutionary very old) derived from photolyase, a bacterial enzyme activated by light and participating in DNA damage repair. In eukaryotes the chryptochromes lost their enzymatic activity. Cryptochromes possess two chromophores: pterin and flavin (a chemical relative of pterin). Pterin absorbs a photon, which causes it to emit energy; the latter is absorbed by flavin, which probably mediates the phosphorylation of a certain domain in cryptochrome. This triggers a signal transduction chain that affects gene regulation in the cell nucleus.
Studies in animals and plants suggest that Cryptochromes play a pivotal role in the generation and maintenance of circadian rhythms . In corals they are part of the mechanism that triggers coordinated spawning for a few nights after a full moon in the spring. Cytochromes are also involved in magnetic orientation of birds during migration and essential for the ability of fruit flies to sense magnetic fields.
SUB1, an Arabidopsis, [Ca.sup.2+]-Binding Protein Involved in Cryptochrome and Phytochrome Coaction.(plant photoreceptors)(Technical)
Jan 19, 2001; Plants rely on multiple photosensory receptors to perceive changes of light quality and quantity and to regulate growth and...