Protein kinase A modulates an endogenous calcium channel, but not the calcium-activated chloride channel, in Xenopus oocytes.
In Xenopus oocytes, Ca2+ influx through an endogenous voltage-gated Ca2+ channel activates a transient outward Cl- current (ICl(Ca)), which is potentiated by cAMP increase. The site of cAMP effect appears to be the Ca2+ channel instead of the Ca(2+)-activated Cl- channel, because cAMP potentiates the Ba2+ current through the Ca2+ channel in a similar way to the ICl(Ca), and cAMP does not potentiate the Ca(2+)-dependent Cl- 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 ICl(Ca). Furthermore, the cAMP/PKA-mediated potentiation of ICl(Ca) was inhibited by both type 1 and type 2A protein phosphatases.
Chen
Y
Y
Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202.
Pollock
J D
JD
Wang
Y
Y
DePaoli-Roach
A A
AA
Yu
L
L
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D002417:Cattle; D018118:Chloride Channels / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D008969:Molecular Sequence Data; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D014981:Xenopus
D015220:Calcium Channels; D018118:Chloride Channels; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D010744:Phosphoric Monoester Hydrolases; D002118:Calcium