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Nitric oxide/cGMP‐mediated regulation of a large conductance Ca‐activated K + (BK Ca ) channel via site‐specific phosphorylation
Author(s) -
Archila Soleil,
Braun Andrew
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a303-b
Subject(s) - phosphorylation , chemistry , nitric oxide , microbiology and biotechnology , protein kinase a , protein phosphorylation , biophysics , biochemistry , biology , organic chemistry
Nitric oxide (NO) is a potent endogenous relaxing agent that decreases vascular smooth muscle tone. NO elevates cGMP, leading to activation of cGMP‐dependent protein kinase Iα (cGKIα) and phosphorylation of several targets, including the BK Ca channel. Phosphorylation of the BK Ca α subunit enhances channel opening, resulting in a greater membrane hyperpolarization, decreased calcium influx and smooth muscle relaxation. Mutagenesis studies have suggested possible sites of cGKIα‐dependent phosphorylation on the BK Ca α subunit, but these have yet to be directly confirmed biochemically. In order to independently identify sites of cGKIα‐induced phosphorylation, site‐specific BK Ca channel mutants were created and examined by in vitro phosphorylation. Antibodies raised against putative phosphorylation sites were produced and isolated to further characterize phosphorylation sites in situ . Results from cGKIα‐induced phosphorylation of site‐specific mutant BK Ca channels in vitro reveal two putative sites of phosphorylation within the cytosolic C‐terminus. Confirmation of these phosphorylation sites will help define the functional effects of phosphorylation on the channel, the overall vasorelaxation effect produced by NO and elucidate problems in vasorelaxation that may be observed in smooth muscle‐related disorders, such as hypertension, incontinence, and asthma. (Funded by CIHR)