Rhythmic gene expression (IMAGE) University of California - San Diego Caption The circadian clock controls the rhythmic expression of hundreds of genes in the cyanobacterium Synechococcus elongatus. The pacemaker of the clock is a core oscillator made up of three proteins: KaiA, KaiB and KaiC. Temporal information is relayed to a transcription factor, RpaA, via two kinases, CikA and SasA, that physically interact with the Kai complex. Credit Goldent Lab, UC San Diego Usage Restrictions Must be used in conjunction with PNAS circadian clock paper. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.