Cryptochromes: Enabling Plants and Animals to Determine Circadian Time

Cryptochromes are flavin-containing blue light photoreceptors related to photolyases—they are found in both plants and animals and have recently been described for bacteria. In plants, cryptochromes perform a variety of functions including the entrainment of circadian rhythms. They serve a similar role in Drosophila and mammals, where the cryptochromes also perform an additional function as an essential component of the circadian clock.