Detection of a highly ouabain sensitive isoform of rat brainstem Na,K-ATPase.
The present work provides evidence for the existence in rat brainstem of a form of Na,K-ATPase catalytic subunit that displays a high affinity for ouabain (Kd about 10(-9) M). Its kinetic identification was made out from studies on dose response curves of ouabain inhibition of Na,K-ATPase activity, ouabain inhibition of Na(+)-dependent phosphorylation from ATP and ouabain stabilized phosphoenzyme formation from inorganic phosphate (Pi). In all these studies this isoform comprises around 11 percent of the total Na,K-ATPase enzyme. The PAGE electrophoretic mobility of its phosphoprotein obtained from Pi in the presence of ouabain is lower than that of the alpha-1 form but it cannot be distinguished from that of alpha-2. Whether this highly ouabain sensitive form corresponds to the alpha-3 isoenzyme or represents the translational product of one of the additional genes described for the large catalytic subunit remains at the moment an open question.
Blanco
G
G
División de Biofisica, Instituto de Investigación Médica Mercedes y Martín Ferreyra, Córdoba, Argentina.
Berberian
G
G
Beaugé
L
L
D000818:Animals; D001933:Brain Stem / Q000201:enzymology*; D004305:Dose-Response Relationship, Drug; D007527:Isoenzymes / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D010042:Ouabain / Q000494:pharmacology*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000302:isolation & purification
D007527:Isoenzymes; D010750:Phosphoproteins; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase