Circadian rhythm is one of the most fascinating and complex biological phenomenon. The circadian clock controls biological activities on daily light-dark cycles in species from cyanobacteria to humans. The circadian clock has three major components: A photoactive pigment (chromophore) for sensing light and transmitting light signals, the circadian clock that oscillates every ~24-hrs, and the genes controlled by the circadian clock to bring about the physiological and behavioral changes.

Several genes have been linked to rhythmicity or circadian behavior of living organisms. In Drosophila, the genes period (per) and timeless (tim), and in Neurospora frequency (frq), have been proposed to be responsible for their circadian rhythm. Recently human and mouse genes (PER1, PER2, PER3) encoding a basic helix-loop-helix (bHLH) and Per-ARNT-Sim (PAS)-domain with significant similarity to the Drosophila Period have been reported. Although, mammalian Clock gene is constitutively expressed (not rhythmic) in the SCN, it may still be an important component of circadian machinery. For example, it has been suggested that Per homologues may dimerize with Clock through PAS-PAS interaction. Several clock-controlled genes have been identified in N. crassa, A. thaliana, D. melanogaster, and mouse that may be responsible for executing the circadian response. However, very little is known about the mammalian photosensory molecules.

It is generally believed that eye contains the photopigments for both visual (imaging) and circadian systems. However, in mice with retinal degeneration (rd) syndrome (loss of rod and cone photoreceptors) and in blind persons, normal circadian rhythm is maintained. This may be explained by the presence of unknown light sensing molecules in nonrod noncone retinal cells.

Plant cryptochromes are 60-70 kDa proteins with high degree of homology with light-activated DNA repair enzymes called DNA-photolyases. Cryptochromes, like photolyases, contain FAD and a pterin as chromophore. However, cryptochromes have no DNA repair activity. Most recently mammalian homolog of the plant blue-light photoreceptors termed cryptochromes have been identified. In A. thaliana, the two cryptochromes (Cry1 and Cry2) have been shown to regulate the plant's response to blue light. In particular, CRY2 gene is implicated in photoperiodism of flowering time. Mouse CRY1 and CRY2, are 606 aa and 569 aa protein, respectively. Cry1 and Cry are specifically expressed in ganglion cell and inner nuclear layers of the mouse retina. CRY1 is expressed at high level in the SCN and oscillates in a circadian manner. Drosophila CRY protein (542 aa) has also been cloned and it is implicated in circadian rhythm setting. Like other genes implicated in circadian mechanism, CRY1 and CRY2 are also expressed in most animal tissues. Therefore, mammalian cryptochromes appears to play an important role in entrainment of the circadian clock.

ADI has produced antibodies to mouse CRY1 and CRY2 using peptide sequences specific for each protein. The appropriate control immunogenic peptides are also available to confirm specificity of antibodies. Availability of these antibodies should help in investigating the physiological roles of CRY1 and CRY2 in circadian rhythm.

 

NT= near N-Terminus; CT=near C-terminus; I= internal; H=human; M=mouse; R=rat;

Control peptides, because of their small size, are not recommended for Western. They should be used in ELISA, dot blot or in antibody blocking studies. "Neat Antiserum" (unpurified crude antiserum) is suitable for ELISA and Western, whereas we recommend using "Affinity pure"(purified over the antigen columns) antibodies for Immunohistochemical applications.

All Products are for in vitro research use only.

List of publications using ADI's antibodies for various circadian proteins 

Cry1 Lee, Choogon 2001 Cell 107, 855-867 Posttranslational Mechanisms Regulate the Mammalian Circadian Clock WB, IP, pdf files.

Cry1m Field, Manuel D. 2000 Neuron 2000 25: 437 Analysis of Clock Proteins in Mouse SCN Demonstrates Phylogenetic Divergence of the Circadian Clockwork and Resetting Mechanisms WB, IHC, scn/brains/frozen/free flaoting.

Cry1 m Bae Kiho 2000 Neuron 30, 525-536 Differential Functions of mPer1, mPer2, and mPer3 in the SCN Circadian Clock IHC, 4%PF, mouse brain.

Cry1 Kume, K et al 1999 Cell 1999 98: 193 mCRY1 and mCRY2 Are Essential Components of the Negative Limb of the Circadian Clock Feedback Loop IHC, 4% paraformal. Brain.

Cry2 Lee, Choogon 2001 Cell 107, 855-867 Posttranslational Mechanisms Regulate the Mammalian Circadian Clock WB, IP, pdf files mouse.

Cry2m Field, Manuel D. 2000 Neuron 2000 25: 437 Analysis of Clock Proteins in Mouse SCN Demonstrates Phylogenetic Divergence of the Circadian Clockwork and Resetting Mechanisms WB, IHC, scn/brains/frozen/free flaoting.

Cry2 Kume, Kazuhiko 1999 Cell 1999 98: 193 mCRY1 and mCRY2 Are Essential Components of the Negative Limb of the Circadian Clock Feedback Loop IHC, 4% paraformal. Brain.

Per 1/Per12-a Zanello, Susana B. 2000 J. Invest. Dermatol. 115: 757-760 Expression of the Circadian Clock Genes clock and period1 in Human Skin IHC, cells fixed forml/glut/triton; human skin.

Per2m LeSauter J 2003 Brain Research, Volume 964, Issue 2, 28 February 2003, Pages 279-287 A short half-life GFP mouse model for analysis of suprachiasmatic nucleus organization IHC. 

Per2m Kapfhamer D 2002 Nature Genetics32, 290 - 295 Mutations in Rab3a alter circadian period and homeostatic response to sleep loss in the mouse IHC, mouse brain PF sections.

Per2m Harmar AJ et al 2002 Cell 109, 497-508 The VPAC2 Receptor Is Essential for Circadian Function in the Mouse Suprachiasmatic Nuclei WB IHC, mper1 their own 4%PF, free floating

Per2 Shigeyoshi, Y et al 2002 Genes to Cells 7 Issue 2 Page 163 Restoration of circadian behavioural rhythms in a period null Drosophila mutant (per01) by mammalian period homologues mPer1 and mPer2 IHC, mper1 from aff bio Flies construct.

Per2 mouse Bae Kiho 2000 Neuron 30, 525-536 Differential Functions of mPer1, mPer2, and mPer3 in the SCN Circadian Clock IHC, 4%PF, mouse brain.

Per2m/hamster Nuesslein-Hildesheim,Barbara 2000 European Journal of Neuroscience, 12, 2856 The circadian cycle of mPER clock gene products in the suprachiasmatic nucleus of the Siberian hamster encodes both daily and seasonal time WB, IHC, hamster brain.

Per2m Field, Manuel D. 2000 Neuron 2000 25: 437 Analysis of Clock Proteins in Mouse SCN Demonstrates Phylogenetic Divergence of the Circadian Clockwork and Resetting Mechanisms WB, IHC, scn/brains/frozen/free flaoting.

Per3m Field, Manuel D. 2000 Analysis of Clock Proteins in Mouse SCN Demonstrates Phylogenetic Divergence of the Circadian Clockwork and Resetting Mechanisms Neuron 2000 25: 437 WB, IHC, scn/brains/frozen/free flaoting

Clock-m Maywood ES 2003 Journal of Neuroendocrinology 15, Issue 4, Page 329 Expression of mCLOCK and Other Circadian Clock-Relevant Proteins in the Mouse Suprachiasmatic Nuclei IHC, IP 4%PF mice brain.

Clock/clo12-a Zanello, Susana B. 2000 J. Invest. Dermatol. 2000 115: 757-760 Expression of the Circadian Clock Genes clock and period1 in Human Skin IHC, cells fixed forml/glut/triton; human skin

Clock/per Takahashi, J S. 1999 Science 1999 September 24; 285: 2076-2077 Enhanced: Narcolepsy Genes Wake Up the Sleep Field.

MOP4 Napoli C et al 2002 Maternal Hypercholesterolemia During Pregnancy Promotes Early Atherogenesis in LDL Receptor-Deficient Mice and Alters Aortic Gene Expression Determined by Microarray Circulation. 2002;105:1360 IHC, mice aorta.