Daily rhythm of nuclear protein kinase activity in rat liver

Abstract
The activity of nuclear protein kinases in rat liver changes during 24 h: with casein as a substrate two maxima of [y‐32P]ATP labelling at 9.00 h and 1.00 h were observed, whereas with histones as substrates only one maximum is registered. 5 x 10‐5M c AMP did no t alter the level or phasing of the kinase activity in the first series of experiments, it increased the level of activity in the second series.