Pharmacological PKA Inhibition: All May Not Be What It Seems

Sci. Signal.  03 Jun 2008:
Vol. 1, Issue 22, pp. re4
DOI: 10.1126/scisignal.122re4
Fig. 2.

Activation of PKA by cAMP. In its inactive state, PKA consists of a tetramer of two regulatory and two catalytic subunits. Each regulatory subunit has two cAMP-binding sites; cAMP binding releases the catalytic subunits, which become bound to ATP and go on to phosphorylate serine and threonine residues that possess the appropriate substrate sequence. The two cAMP-binding sites (A and B) on each regulatory subunit are shown. C, protein kinase A catalytic subunit; R, protein kinase A regulatory subunit.