[Nuclear translocation and effect of cAMP-dependent protein kinase on transcription]

The influence of cAMP-dependent pig brain protein kinase and its subunits on transcription in vitro was studied. The increase in the template activity of chromatin isolated from the nuclei after treatment with the catalytic subunit was observed. The regulatory subunit of protein kinase was found to increase the number of binding sites for RNA polymerase on chromatin. The cAMP-dependent pig brain protein kinase was found to phosphorylate the sigma-factor of Escherichia coli RNA polymerase. This phosphorylation led to the increase of the RNA polymerase activity on phage lambda DNA. The nuclear translocation of the protein kinase and its subunits was shown to take place. In the cells with a low cAMP level (SV40 3T3) the transfer of the regulatory subunit to the nucleus was not detected. Only upon addition of cAMP and a subsequent formation of the cAMP-regulatory subunit complex, nuclear translocation was observed in these cells. The dependence of nuclear translocation of the cAMP-dependent protein kinase on cAMP level in the cell is proposed.