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This Article Full Text Full Text (PDF) All Versions of this Article: 297/4/L758    most recent 90518.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Zhu, S. Articles by Barman, S. A. PubMed PubMed Citation Articles by Zhu, S. Articles by Barman, S. A.

Mutation of protein kinase C phosphorylation site S1076 on -subunits affects BK_Ca channel activity in HEK-293 cells

Department of ¹Pharmacology and Toxicology, Medical College of Georgia, Augusta, Georgia; Department of ²Biochemistry and Molecular Biology, Medical College of Georgia, Augusta, Georgia; Department of ³Vascular Biology Center, Medical College of Georgia, Augusta, Georgia

Submitted 14 October 2008 ; accepted in final form 3 July 2009

Large conductance, calcium- and voltage-activated potassium (BK_Ca) channels are important modulators of pulmonary vascular smooth muscle membrane potential, and phosphorylation of BK_Ca channels by protein kinases regulates pulmonary arterial smooth muscle function. However, little is known about the effect of phosphorylating specific channel subunits on BK_Ca channel activity. The present study was done to determine the effect of mutating protein kinase C (PKC) phosphorylation site serine 1076 (S1076) on transfected human BK_Ca channel -subunits in human embryonic kidney (HEK-293) cells, a heterologous expression system devoid of endogenous BK_Ca channels. Results showed that mutating S1076 altered the effect of PKC activation on BK_Ca channels in HEK-293 cells. Specifically, the phospho-deficient mutation BK_Ca-(S1076A)/β₁ attenuated the excitatory effect of the PKC activator phorbol myristate acetate (PMA) on BK_Ca channels, whereas the phospho-mimetic mutation BK_Ca-(S1076E)/β₁ increased the excitatory effect of PMA on BK_Ca channels. In addition, the phospho-null mutation S1076A blocked the activating effect of cGMP-dependent protein kinase G (PKG) on BK_Ca channels. Collectively, these results suggest that specific putative PKC phosphorylation site(s) on human BK_Ca channel -subunits influences BK_Ca channel activity, which may subsequently alter pulmonary vascular smooth muscle function and tone.

channel subunits