The Arabidopsis pseudo-response regulator, APRR1, has a unique structural design containing a pseudo-receiver domain and a C-terminal CONSTANS motif. This protein was originally characterized as a presumed component of the His-to-Asp phosphorelay systems in Arabidopsis thaliana. Recently, it was reported that APRR1 is identical to the TOC1 gene product, a mutational lesion of which affects the ...

Prokaryotic cyanobacteria express robust circadian (daily) rhythms under the control of a timing mechanism that is independent of the cell division cycle. This biological clock orchestrates global regulation of gene expression and controls the timing of cell division. Proteins that may be involved in input pathways have been identified. Mutational screening has identified three clock genes that...

A small cluster of approximately 20,000 neurons in the ventral hypothalamus provide the body with key time-keeping signals and drive circadian rhythms. This circadian clock exhibits surprisingly complex substructures, with inputs from the retina, and outputs to other brain structures. Rather little is known of the neurotransmitters involved, or their regulation.