Cycle (gene)
gene
Cycle (cyc) is a gene in Drosophila melanogaster that encodes the CYCLE protein (CYC). The Cycle gene (cyc) is expressed in a variety of cell types in a circadian manner. It is involved in controlling both the sleep-wake cycle and circadian regulation of gene expression by promoting transcription in a negative feedback mechanism. The cyc gene is located on the left arm of chromosome 3 and codes for a transcription factor containing a basic helix–loop–helix (bHLH) domain and a PAS domain. The 2.17 kb cyc gene is divided into 5 coding exons totaling 1,625 base pairs which code for 413 aminos acid residues. Currently 19 alleles are known for cyc . Orthologs performing the same function in other species include basic helix-loop-helix ARNT-like protein 1 (ARNTL) and Aryl hydrocarbon receptor nuclear translocator-like 2 (ARNTL2).
Function
Cycle is primarily known for its role in the genetic transcription-translation feedback loop that generates circadian rhythms in Drosophila. In the cell nucleus, the CYCLE protein (CYC) forms a heterodimer with a second bHLH-PAS protein, CLOCK (CLK). This CYC-CLK protein complex binds to E-box elements in promoter regions of the genes period and timeless, functioning as a transcription factor in the translation of the proteins PER and TIM. After the PER and TIM proteins accumulate in the cytoplasm and bind together, the PER-TIM complex translocates to the nucleus.
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This entry incorporates text from “Cycle (gene)” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.