Recombinant fragment of protein kinase inhibitor blocks cyclic AMP-dependent gene transcription

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Science  23 Oct 1987:
Vol. 238, Issue 4826, pp. 530-533
DOI: 10.1126/science.2821622


Transcriptional regulation by cyclic adenosine monophosphate (cAMP) in mammalian cells could be mediated by a phosphoprotein substrate of the cAMP-dependent protein kinase or, as in prokaryotes, by a cAMP-binding protein. Two synthetic genes that code for an active fragment of the protein inhibitor of this kinase and a mutant inactive fragment were constructed and used to distinguish these alternatives. Transient expression of the active peptide product specifically inhibited the cAMP-stimulated expression of a cotransfected reporter gene by more than 90 percent, whereas the expression of the inactive peptide did not alter cAMP-stimulated gene expression. The results indicate that an active kinase catalytic subunit is a necessary intermediate in the cAMP stimulation of gene transcription.