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Specific phosphorylation sites underlie the stimulation of a large conductance, Ca(2+)-activated K(+) channel by cGMP-dependent protein kinase.

Authors: Kyle, BD  Hurst, S  Swayze, RD  Sheng, J  Braun, AP 
Citation: Kyle BD, etal., FASEB J. 2013 May;27(5):2027-38. doi: 10.1096/fj.12-223669. Epub 2013 Feb 13.
Pubmed: (View Article at PubMed) PMID:23407708
DOI: Full-text: DOI:10.1096/fj.12-223669

Smooth muscle contractility and neuronal excitability are regulated by large conductance, Ca(2+)-activated K(+) (BKCa) channels, the activity of which can be increased after modulation by type I cGMP-dependent protein kinase (cGKI) via nitric oxide (NO)/cGMP signaling. Our study focused on identifying key phosphorylation sites within the BKCa channel underlying functional enhancement of channel activity by cGKI. BKCa channel phosphorylation by cGKIalpha was characterized biochemically using radiolabeled ATP, and regulation of channel activity by NO/cGMP signaling was quantified in rat aortic A7r5 smooth muscle cells by cell-attached patch-clamp recording. Serine to alanine substitutions at 3 of 6 putative cGKI phosphorylation sites (Ser691, Ser873, and Ser1112) in the BKCa alpha subunit individually reduced direct channel phosphorylation by 25-60% and blocked BKCa activation by either an NO donor or a membrane-permeable cGMP by 80-100%. Acute inhibition of cGKI prevented stimulus-evoked enhancement of BKCa channel activity. Our data further suggest that augmentation of BKCa activity by NO/cGMP/cGKI signaling requires phosphorylation at all 3 sites and is independent of elevations in [Ca(2+)]i. Phosphorylation of 3 specific Ser residues within the murine BKCa alpha subunit by cGKIalpha accounts for the enhanced BKCa channel activity induced by elevated [cGMP]i in situ.

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CRRD Object Information
CRRD ID: 7777099
Created: 2014-01-02
Species: All species
Last Modified: 2014-01-02
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.