CLOCK
protein-coding gene in the species Homo sapiens
CLOCK (backronym for circadian locomotor output cycles kaput) is a gene encoding a basic helix-loop-helix-PAS transcription factor that is known to affect both the persistence and period of circadian rhythms.
Research shows that the CLOCK gene plays a major role as an activator of downstream elements in the pathway critical to the generation of circadian rhythms.
Discovery
The CLOCK gene was first identified in 1997 by Joseph Takahashi and his colleagues. Takahashi used forward mutagenesis screening of mice treated with N-ethyl-N-nitrosourea to create and identify mutations in key genes that broadly affect circadian activity. The CLOCK mutants discovered through the screen displayed an abnormally long period of daily activity. This trait proved to be heritable. Mice bred to be heterozygous showed longer periods of 24.4 hours compared to the control 23.3 hour period. Mice homozygous for the mutation showed 27.3 hour periods, but eventually lost all circadian rhythmicity after several days in constant darkness. That showed that "intact CLOCK genes" are necessary for normal mammalian circadian function, as these mutations were semidominant.
Function
CLOCK protein has been found to play a central role as a transcription factor in the circadian pacemaker.
This brief starts where responsible research should: with the source description of “CLOCK” as protein-coding gene in the species Homo sapiens. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the science & nature register because the source frames it as protein-coding gene in the species Homo sapiens. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Stable identifiers, scientific names and standards terminology offer the best bridge between this overview and specialist evidence. The source revision retrieved here is dated Sep 7, 2026. The linked authority identifier is Q14908739. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1997.
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This entry incorporates text from “CLOCK” 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.