The catalytic subunits are inactive when bound to the regulatory subunits and are activated by cAMP binding to the regulatory subunits inducing the release and activation of the catalytic subunits [8].
The dual-specific A-kinase anchor protein 10 (AKAP10) is member of a diverse protein family, which binds to the regulatory subunit of protein kinase A (PKA, for a review on AKAP10, see [61]).
This second messenger binds to the regulatory subunit of PKA and releases its catalytic subunit, which phosphorylates DARPP-32 at threonine 34 (Thr34, positioned according to the rat sequence).
The PKA holoenzyme is anchored and does not diffuse, but after cAMP binds to the regulatory subunit, the catalytic subunit is released, diffuses throughout the cell and phosphorylates various targets including PDE4s.
The inactive complex disassociates when cAMP binds to the regulatory subunit, which releases the active protein-kinase component [ 67].
Cyclic AMP (cAMP) produced by the adenylate cyclase binds to the regulatory subunit of the the cAMP-dependent protein kinase A (RPKA), releasing the catalytic subunit PKA (CPKA).
Upon activation of the GPCR or Ras pathways adenylate cyclase increases cAMP production, which in turn binds to the regulatory subunit (PkaR) of PkaA, releasing the active catalytic subunit to phosphorylate downstream targets [ 21, 23].
Furthermore, we clarified that MyD88 could bind to the regulatory subunit of PI3-K, p85, and activate PI3-K/Akt/GSK-3 β/Snail pathway to induce EMT and tumor metastasis.
Upon stimulation cAMP binds to the regulatory subunits, causing a conformational change which results in the release of catalytic subunits.
When the cAMP concentration increases and binds to the regulatory subunits of protein kinas A, the subunits dissociate from the protein complex and the kinase is activated [ 11].
