Abstract
We report the identification, characterization, and cloning of another novel Drosophila clock gene, cycle (cyc). Homozygous cyc flies are completely arrhythmic. Heterozygous cyc/+ flies are rhythmic but have altered periods, indicating that the cyc locus has a dosage effect on period. The molecular circadian phenotype of homozygous cyc flies is like homozygous Clk flies presented in the accompanying paper: mutant flies have little or no transcription of the per and tim genes. Cloning of the gene indicates that it also encodes a bHLH-PAS transcription factor and is a Drosophila homolog of the human protein BMAL1. cyc is a nonsense mutation, consistent with its strong loss-of-function phenotype. We propose that the CYC:CLK heterodimer binds to per and tim E boxes and makes a major contribution to the circadian transcription of Drosophila clock genes.
Publication types
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Comparative Study
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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ARNTL Transcription Factors
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Amino Acid Sequence
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Animals
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Basic Helix-Loop-Helix Transcription Factors
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Behavior, Animal
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Chromosome Mapping
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Circadian Rhythm / genetics*
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Cloning, Molecular
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Drosophila / genetics*
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Drosophila Proteins*
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Gene Dosage
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Genes, Insect
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Helix-Loop-Helix Motifs
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Insect Proteins / biosynthesis*
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Models, Genetic
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Molecular Sequence Data
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Mutation
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Nuclear Proteins / biosynthesis*
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Period Circadian Proteins
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Sequence Homology, Amino Acid
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Trans-Activators / genetics*
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Transcription Factors / genetics
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Transcription, Genetic
Substances
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ARNTL Transcription Factors
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BMAL1 protein, human
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Basic Helix-Loop-Helix Transcription Factors
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Drosophila Proteins
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Insect Proteins
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Nuclear Proteins
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PER protein, Drosophila
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Period Circadian Proteins
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Trans-Activators
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Transcription Factors
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cyc protein, Drosophila
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tim protein, Drosophila