| Figure 5-1.2 |
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| Regulation of PKA by cAMP binding | |
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| In the absence of cAMP, PKA exists as a complex in which the C domain is held in an inactive state by association with the R subunit. When cAMP levels increase, the R subunit binds cAMP and dissociates from the C subunit, which is now active and can phosphorylate substrates. |