A morning-induced, phosphorylation-gated repressor times evening gene expression: a new way for circadian clocks to use an old trick.

In this issue of Molecular Cell, Sancar et al. (2011) show that a morning-induced transcriptional repressor with a phosphorylation-gated half-life is a key cog in driving evening gene expression, adding new insights into how circadian clocks achieve phase-specific gene expression.