Protein kinase A modulates an endogenous calcium channel, but not the calcium‐activated chloride channel, in Xenopus oocytes

[摘要]

In Xenopus oocytes, Ca²⁺ influx through an endogenous voltage-gated Ca²⁺ channel activates a transient outward Cl⁻ current (I _CI(Ca)), which is potentiated by cAMP increase. The site of cAMP effect appears to be the Ca²⁺ channel instead of the Ca²⁺-activated Cl⁻ channel, because cAMP potentiates the Ba²⁺ current through the Ca²⁺ channel in a similar way to the I _Cl(Ca), and cAMP does not potentiate the Ca²⁺-dependent CI⁻ current in cells treated with Ca²⁺ ionophore. Using the catalytic subunit of protein kinase A (PKA) and PKA inhibitors, it was shown that PKA is both necessary and sufficient for the cAMP effect on I _CI(Ca). Furthermore, the cAMP/PKA-mediated potentiation of I _cI(Ca) was inhibited by both type 1 and type 2A protein phosphatases.

[学科分类] 生物化学/生物物理

[关键词] Protein kinase A;Phosphatase;Calcium channel;Xenopus oocyte;Calcium ionophore