Evidence for involvement of A-kinase anchoring protein in activation of rat arterial KATP channels by protein kinase A
- 1We have investigated the possible role of A-kinase anchoring proteins (AKAPs) in protein kinase A (PKA) signalling to ATP-sensitive K+ (KATP) channels of rat isolated mesenteric arterial smooth muscle cells using whole-cell patch clamp and peptides that inhibit PKA-AKAP binding.
- 2Intracellular Ht31 peptide (20 μm), which inhibits the PKA-AKAP interaction, blocked KATP current activation by either dibutyryl cAMP or calcitonin gene-related peptide. Ht31-proline (20 μm), which does not inhibit PKA binding to AKAP, did not block KATP current activation.
- 3Ht31 reduced KATP current activated by pinacidil and also prevented its inhibition by Rp-cAMPS, effects consistent with Ht31 blocking steady-state KATP channel activation by PKA. However, Ht31 did not prevent KATP current activation by the catalytic subunit of PKA.
- 4An antibody to the RII subunit of PKA showed localization of PKA near to the cell membrane. Our results provide evidence that both steady-state and receptor-driven activation of KATP channels by PKA involve the localization of PKA by an AKAP.