An ouabain-sensitive Na+,K(+)-ATPase in tentacles of the sea anemone Stichodactyla helianthus.
Tentacles of Stichodactyla helianthus contain an ouabain-inhibitable, (Na+,K+)-stimulated ATPase. The K0.5 for Na+ was 24 mM and for K+, 3.2 mM. The apparent affinity for ouabain was low, I50 = 10(-4) M. The order of cation affinities was Rb+ > K+ > NH4+ = Cs+. The catalytic subunit of the enzyme comprised a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, M(r) = 105 kDa, that was phosphorylated by [32P]ATP in the presence of NaCl and dephosphorylated by the addition of KCl. The alpha subunit was weakly reactive with antibodies directed against the rat alpha subunit.
Specht
S C
SC
Department of Pharmacology, University of Puerto Rico, San Juan 00901.
Lopez-Rosado
R
R
Santos-Berrios
C
C
Figueroa-Nieves
R
R
D000818:Animals; D002412:Cations / Q000378:metabolism; D015151:Immunoblotting; D007700:Kinetics; D008970:Molecular Weight; D010042:Ouabain / Q000378:metabolism / Q000494:pharmacology; D010766:Phosphorylation; D051381:Rats; D012615:Sea Anemones / Q000201:enzymology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D014018:Tissue Distribution
D002412:Cations; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase