Genes controlled by the fruit fly's internal clock and their role in daily gene activity in different tissues

CLK binding occurs at at least 800 sites with peak activity in the early night.

• The CLK partner protein CYCLE is present at most CLK binding sites.
• PER, a transcriptional repressor, joins the CLK/CYC complex 4-6 hours later.
• Approximately 30% of target genes exhibit cycles of RNA polymerase II binding.
• Many genes produce cycling RNAs that were not previously identified in RNA cycling studies.
• Different RNA isoforms and tissue heterogeneity may contribute to observed cycling.
• CLK targets vary across tissues, suggesting distinct regulatory mechanisms at play.

Simplified