title: Two period homologs: circadian expression and photic regulation in the suprachiasmatic nuclei.
abstract: We have characterized a mammalian homolog of the Drosophila period gene and designated it Per2. The PER2 protein shows >40% amino acid identity to the protein of another mammalian per homolog (designated Per1) that was recently cloned and characterized. Both PER1 and PER2 proteins share several regions of homology with the Drosophila PER protein, including the protein dimerization PAS domain. Phylogenetic analysis supports the existence of a family of mammalian per genes. In the mouse, Per1 and Per2 RNA levels exhibit circadian rhythms in the SCN and eyes, sites of circadian clocks. Both Per1 and Per2 RNAs in the SCN are increased by light exposure during subjective night but not during subjective day. The results advance our knowledge of candidate clock elements in mammals.
authors.affiliation: Laboratory of Developmental Chronobiology, Pediatric Service, Massachusetts General Hospital and Harvard Medical School, Boston 02114, USA.
authors.forename: L P
authors.initials: LP
authors.lastname: Shearman
authors.forename: M J
authors.initials: MJ
authors.lastname: Zylka
authors.forename: D R
authors.initials: DR
authors.lastname: Weaver
authors.forename: L F
authors.initials: LF
authors.lastname: Kolakowski
authors.forename: S M
authors.initials: SM
authors.lastname: Reppert
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins; D002940:Circadian Rhythm; D018076:DNA, Complementary; D004330:Drosophila; D029721:Drosophila Proteins; D005786:Gene Expression Regulation / Q000528:radiation effects*; D006801:Humans; D008027:Light; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D005810:Multigene Family; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000737:chemistry*; D056950:Period Circadian Proteins; D010802:Phylogeny; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013493:Suprachiasmatic Nucleus / Q000378:metabolism* / Q000528:radiation effects; D014157:Transcription Factors
chemical_list: D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D029721:Drosophila Proteins; D009687:Nuclear Proteins; C539040:PER protein, Drosophila; C539022:PER1 protein, human; C421902:PER2 protein, human; C539023:Per1 protein, mouse; C513312:Per2 protein, mouse; D056950:Period Circadian Proteins; D014157:Transcription Factors