Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Resealed chromaffin-granule ;ghosts' were used to study the steady-state kinetics of catecholamine transport. The pump has a high affinity for (-)-noradrenaline, (-)-adrenaline, tyramine and 5-hydroxytryptamine (serotonin), but a lower affinity for (+)-noradrenaline. The measured rates of incorporation do not conform to Michaelis-Menten kinetics, but affinity constants for the former substrates are in the range 8-18mum. Reserpine is a potent inhibitor. Incorporation as a function of ATP concentration also fails to show simple kinetics; the affinity constant for ATP is deduced to be about 3mm at 1mm-MgCl(2). Adenylyl (betagamma-methylene)diphosphonate is a competitive inhibitor at low concentrations, but inhibits more strongly at high concentrations. The pump has a transition temperature at 29 degrees C and does not seem to be identical with the Mg(2+)-stimulated adenosine triphosphatase of chromaffin granules.
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PMID:Steady-state kinetics of catecholamine transport by chromaffin-granule "ghosts". 446 85

The present study was designed to investigate the role of the sodium potassium adenosine triphosphatase (the Na(+)K(+) ATPase) in relaxation of bovine isolated bronchioles by a new NO donor, GEA 3175 (3-(3-chloro-2-methylphenyl)-5-[[(4-methylphenyl)sulphonyl]amino]-)hydroxide)). Bronchioles were mounted in a wire myograph for isometric tension recordings and contracted with 5-hydroxytryptamine (5-HT) or a K(+) rich solution. Concentration-dependent relaxations evoked by GEA 3175 were inhibited by ouabain or K(+) free solution. The guanylyl cyclase inhibitor 1H-[1,2,4]-oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, 3 microM) and ouabain (10 nM) reduced GEA 3175-evoked relaxations to the same extent without any additive effect. Iberiotoxin (10 nM), an inhibitor of large conductance Ca(2+)-activated K(+) channels inhibited GEA 3175-evoked relaxations to the same extent as ouabain. Combining ouabain and iberiotoxin completely abolished GEA 3175 relaxation. An inhibitor of protein kinase G (PKG), Rp-beta-phenyl-1,N(2)-etheno-8-bromo-guanosine-3'-5'-cyclic monophosphorothioate (Rp-8-Br-PET-cGMPs), slightly reduced GEA 3175-induced relaxations. An inhibitor of cyclic AMP-dependent kinase (PKA), Rp-adenosine-3'-5'-cyclic phosphorothioate (Rp-cAMPs), inhibited the GEA 3175-induced relaxations to the same extent as ouabain. Inhibition of both PKG and PKA abolished GEA 3175 relaxation. The study provides evidence that the NO donor GEA 3175 causes guanylyl cyclase-dependent relaxations, taking place through cyclic GMP and cyclic AMP-dependent protein kinases followed by opening of large conductance Ca(2+)-activated K(+) channels and activation of smooth muscle Na(+)K(+) ATPase.
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PMID:Involvement of guanylyl cyclase, protein kinase A and Na+ K+ ATPase in relaxations of bovine isolated bronchioles induced by GEA 3175, an NO donor. 1602 94