title: Guanylyl cyclase stimulatory coupling to K(Ca) channels.
abstract: We coexpressed the human large-conductance, calcium-activated K (K(Ca)) channel (alpha- and beta-subunits) and rat atrial natriuretic peptide (ANP) receptor genes in Xenopus oocytes to examine the mechanism of guanylyl cyclase stimulatory coupling to the channel. Exposure of oocytes to ANP stimulated whole cell K(Ca) currents by 21 +/- 3% (at 60 mV), without altering current kinetics. Similarly, spermine NONOate, a nitric oxide donor, increased K(Ca) currents (20 +/- 4% at 60 mV) in oocytes expressing the channel subunits alone. Stimulation of K(Ca) currents by ANP was inhibited in a concentration-dependent manner by a peptide inhibitor of cGMP-dependent protein kinase (PKG). Receptor/channel stimulatory coupling was not completely abolished by mutating the cAMP-dependent protein kinase phosphorylation site on the alpha-subunit (S869; Nars M, Dhulipals PD, Wang YX, and Kotlikoff MI. J Biol Chem 273: 14920-14924, 1998) or by mutating a neighboring consensus PKG site (S855), but mutation of both residues virtually abolished coupling. Spermine NONOate also failed to stimulate channels expressed from the double mutant cRNAs. These data indicate that nitric oxide donors stimulate K(Ca) channels through cGMP-dependent phosphorylation and that two serine residues (855 and 869) underlie this stimulatory coupling.
authors.affiliation: Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6046, USA.
authors.forename: M
authors.initials: M
authors.lastname: Nara
authors.forename: P D
authors.initials: PD
authors.lastname: Dhulipala
authors.forename: G J
authors.initials: GJ
authors.lastname: Ji
authors.forename: U R
authors.initials: UR
authors.lastname: Kamasani
authors.forename: Y X
authors.initials: YX
authors.lastname: Wang
authors.forename: S
authors.initials: S
authors.lastname: Matalon
authors.forename: M I
authors.initials: MI
authors.lastname: Kotlikoff
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D020134:Catalytic Domain / Q000235:genetics; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D006162:Guanylate Cyclase / Q000378:metabolism*; D006801:Humans; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000201:enzymology; D016296:Mutagenesis / Q000502:physiology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009589:Nitrogen Oxides; D009865:Oocytes / Q000502:physiology; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology; D010766:Phosphorylation; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated; D051381:Rats; D017461:Receptors, Atrial Natriuretic Factor / Q000235:genetics / Q000378:metabolism; D013096:Spermine / Q000031:analogs & derivatives / Q000494:pharmacology; D014982:Xenopus laevis
chemical_list: D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; D010455:Peptides; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; C091861:spermine nitric oxide complex; D013096:Spermine; C064719:iberiotoxin; D009320:Atrial Natriuretic Factor; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor