Cryptochrome

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Identifiers
Symbol CRY1
Alt. Symbols PHLL1
Entrez 1407
HUGO 2384
OMIM 601933
RefSeq NM_004075
UniProt Q16526
Other data
Locus Chr. 12 q23-q24.1
Identifiers
Symbol CRY2
Entrez 1408
HUGO 2385
OMIM 603732
RefSeq NM_021117
UniProt Q49AN0
Other data
Locus Chr. 11 p11.2

Cryptochrome is a name used for the blue light photoreceptors of plants and animals. The word cryptochrome derives from the greek κρυπτό χρώμα (krupto chroma), meaning hidden colour. It is now used to describe a specific subset of blue light receptors, a family of flavoproteins that regulate germination, elongation, photoperiodism, and other responses in higher plants. Blue light also mediates phototropism, but this response is now known to have its own set of photoreceptors, the phototropins.

Cryptochromes are found in all plant species. Two similar cryptochromes exist in most plants: CRY1 and CRY2. Cryptochrome is ancient, and is derived from photolyase, a bacterial enzyme activated by light and participating in DNA damage repair. In eukaryotes the chryptochromes lost their enzymatic activity.

Cryptochrome possesses two chromophores: pterin and flavin (a chemical relative of pterin). Not much is known about the way cryptochromes exercise their physiological effects. 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.

Cryptochromes are also found in insects and mammals. The two cryptochromes found in mammals play a pivotal role in the generation and maintenance of circadian rhythms [1] [2] .

A recent study suggests that cryptochromes allow migratory birds to navigate by sensing magnetic fields. [3] Other theories suggest that this ability lies dormant in all mammals. In the human genome the genes coding for CRY1 and CRY2 are found on chromosomes 12 and 11, respectively.

Cryptochromes are also found in corals, which use them to trigger coordinated spawning for a few nights after a full moon in the spring [4].

[edit] References

  1. ^ Roenneberg, T.; Foster R.G. (1997). "Twilight times: light and the circadian system". Photochem. Photobiol. 66: 549–561. doi:10.1111/j.1751-1097.1997.tb03188.x. 
  2. ^ Foster, R.G. (1998). "Shedding light on the biological clock". Neuron 20: 829–832. doi:10.1016/S0896-6273(00)80464-X. 
  3. ^ Heyers, Dominik; Martina Manns, Harald Luksch, Onur Güntürkün, Henrik Mouritsen (September 2007). "A visual pathway links brain structures active during magnetic compass orientation in migratory birds". PLos ONE 2 (9): e937. doi:10.1371/journal.pone.0000937. 
  4. ^ Levy, O.; Appelbaum L., Leggat W., Gothlif Y., Hayward D.C., Miller D.J., Hoegh-Guldberg O. (2007-10-19). "Light-responsive cryptochromes from a simple multicellular animal, the coral acropora millepora" (abstract). Science 318 (5849): 467–470. doi:10.1126/science.1145432. 


[edit] External links

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Protein: flavoproteins