Reciprocal modulation of ATP-sensitive K+ channel activity in rat ventricular myocytes by phosphorylation of tyrosine and serine/threonine residues.
The modulation of ATP-sensitive K+ channel (KATP) activity by specific phosphorylation or dephosphorylation of tyrosine and serine/threonine residues was examined in rat ventricular myocytes using the inside-out patch configuration of the patch clamp technique. The run-down process was suppressed by okadaic acid but accelerated by sodium orthovanadate. After run-down of the channels, the ATP-induced reactivation was blocked by H-7, but enhanced by genistein. The channel activity was decreased by protein phosphatase 2A. However, the activity of partially run-down channels was increased by protein tyrosine phosphatase 1B. Our results suggest that KATP channel activity can be inhibited by phosphorylation of tyrosine residues and stimulated by phosphorylation of serine/threonine residues.
Kwak
Y G
YG
Department of Pharmacology, Chonbuk National University Medical School, Chonju, South Korea.
Park
S K
SK
Cho
K P
KP
Chae
S W
SW
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D009206:Myocardium / Q000378:metabolism; D010766:Phosphorylation; D015221:Potassium Channels / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012694:Serine / Q000378:metabolism; D013912:Threonine / Q000378:metabolism; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism
D015221:Potassium Channels; D013912:Threonine; D014443:Tyrosine; D012694:Serine; D000255:Adenosine Triphosphate