Putative human blue-light photoreceptors hCRY1 and hCRY2 are flavoproteins.
Recently, a human cDNA clone with high sequence homology to the photolyase/blue-light photoreceptor family was identified. The putative protein encoded by this gene exhibited a strikingly high (48% identity) degree of homology to the Drosophila melanogaster (6-4) photolyase [Todo et al. (1996) Science 272, 109-112]. We have now identified a second human gene whose amino acid sequence displays 73% identity to the first one and have named the two genes CRY1 and CRY2, respectively. The corresponding proteins hCRY1 and hCRY2 were purified and characterized as maltose-binding fusion proteins. Similar to other members of the photolyase/blue-light photoreceptor family, both proteins were found to contain FAD and a pterin cofactor. Like the plant blue-light photoreceptors, both hCRY1 and hCRY2 lacked photolyase activity on the cyclobutane pyrimidine dimer and the (6-4) photoproduct. We conclude that these newly discovered members of the photolyase/photoreceptor family are not photolyases and instead may function as blue-light photoreceptors in humans.
Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill 27599, USA.
D S
DS
Hsu
X
X
Zhao
S
S
Zhao
A
A
Kazantsev
R P
RP
Wang
T
T
Todo
Y F
YF
Wei
A
A
Sancar
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D056931:Cryptochromes; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004255:Deoxyribodipyrimidine Photo-Lyase / Q000235:genetics; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000201:enzymology / Q000235:genetics; D005136:Eye Proteins; D005420:Flavoproteins / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D010786:Photoreceptor Cells / Q000737:chemistry*; D017956:Photoreceptor Cells, Invertebrate; D010957:Plasmids; D043562:Receptors, G-Protein-Coupled; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D013053:Spectrophotometry
C538963:CRY1 protein, human; C538966:CRY2 protein, human; D056931:Cryptochromes; D017931:DNA Primers; D018076:DNA, Complementary; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; D043562:Receptors, G-Protein-Coupled; D011994:Recombinant Proteins; C119828:cry protein, Drosophila; D004255:Deoxyribodipyrimidine Photo-Lyase