Cryptochrome

Cryptochrome-1
Crystallographic structure of Cryptochrome-1
Identifiers
Symbol	CRY1
NCBI gene	1407
HGNC	2384
OMIM	601933
PDB	5T5X
RefSeq	NP_004066
UniProt	Q16526
Other data
Locus	Chr. 12 q23.3
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Cryptochromes (from the Greek κρυπτός χρώμα, "hidden colour") are a class of flavoproteins found in plants and animals that are sensitive to blue light. They are involved in the circadian rhythms and the sensing of magnetic fields in a number of species. The name cryptochrome was proposed as a portmanteau combining the chromatic nature of the photoreceptor, and the cryptogamic organisms on which many blue-light studies were carried out.^[1][2]

The genes CRY1 and CRY2 encode the proteins CRY1 and CRY2, respectively.^[3] Cryptochromes are classified into plant Cry and animal Cry. Animal Cry can be further categorized into insect type (Type I) and mammal-like (Type II). CRY1 is a circadian photoreceptor whereas CRY2 is a clock repressor which represses Clock/Cycle (Bmal1) complex in insects and vertebrates.^[4] In plants, blue-light photoreception can be used to cue developmental signals.^[5] Besides chlorophylls, cryptochromes are the only proteins known to form photoinduced radical-pairs in vivo.^[6] These appear to enable some animals to detect magnetic fields.

Cryptochromes have been the focus of several current efforts in optogenetics. Employing transfection, initial studies on yeast have capitalized on the potential of CRY2 heterodimerization to control cellular processes, including gene expression, by light.