Changes in the number of Na+-K+-ATPase alpha-subunits, Na+-K+-ATPase activity and glycogen content of the crucian carp (Carassius carassius) brain were examined to elucidate relative roles of energy demand and supply in adaptation to seasonal anoxia. Fish were collected monthly around the year from the wild for immediate laboratory assays. Equilibrium dissociation constant and Hill coefficient ...

The copper-transporting P-type ATPases (Cu-ATPases), ATP7A and ATP7B, are essential for the regulation of intracellular copper homeostasis. In this report we describe new roles for glutathione (GSH) and glutaredoxin1 (GRX1) in Cu homeostasis through their regulation of Cu-ATPase activity. GRX1 is a thiol oxidoreductase that catalyzes the reversible reduction of GSH-mixed disulfides to their res...

This work utilizes Fe(2+)-catalyzed cleavages and molecular modeling to obtain insight into conformations of cytoplasmic domains and ATP-Mg(2+) binding sites of Na(+),K(+)-ATPase. In E(1) conformations the ATP-Fe(2+) complex mediates specific cleavages at 712VNDS (P domain) and near 440VAGDA (N domain). In E(2)(K), ATP-Fe(2+) mediates cleavages near 212TGES (A domain), near 440VAGDA, and betwee...

CopA from the extreme thermophile Archaeoglobus fulgidus is a P-type ATPase that transports Cu(+) and Ag(+) and has individual metal-binding domains (MBDs) at both N- and C-termini. We expressed and purified full-length CopA as well as constructs with MBDs deleted either individually or collectively. Cu(+) and Ag(+)-dependent ATPase assays showed that full-length CopA had submicromolar affinity...

The P-type ATPases affected in Menkes and Wilson diseases, ATP7A and ATP7B, respectively, are key copper transporters that regulate copper homeostasis. The N termini of these proteins are critical in regulating their function and activity, and contain six copper-binding motifs MxCxxC. In this study, we describe the identification of glutaredoxin (GRX1) as an interacting partner of both ATP7A an...

To investigate whether the sodium-potassium pump or Na+,K+-ATPase concentration in muscles is related to the capacity for muscle performance, the 3H-ouabain binding site concentration or 3-O-methylflourescein phosphatase activity was determined in samples of heart ventricular muscles from trained rats, cardiomyopathic hamsters, and human subjects. These methods have earlier been shown to quanti...

ArsA, the catalytic subunit of an anion-translocating ATPase, has two consensus nucleotide binding sites, one N-terminal and one C-terminal. A mutation producing a G15C substitution in the N-terminal domain resulted in substantial reductions in arsenite resistance, transport, and ATPase activity. A second site revertant (A344V) adjacent to the C-terminal nucleotide binding site was previously s...

Prolonged exercise followed by a brief period of reduced activity has been shown to result in an overshoot in maximal sarcoplasmic reticulum (SR) Ca(2+)-ATPase activity [maximal velocity (V(max))] in rat locomoter muscles (Ferrington DA, Reijneveld JC, Bär PR, and Bigelow DJ. Biochim Biophys Acta 1279: 203-213, 1996). To investigate the functional significance and underlying mechanisms for the ...

Tupling, R., H. Green, G. Senisterra, J. Lepock, and N. McKee. Ischemia-induced structural change in SR Ca21ATPase is associated with reduced enzyme activity in rat muscle. Am J Physiol Regulatory Integrative Comp Physiol 281: R1681–R1688, 2001.—In this study, we employed an in vivo model of prolonged ischemia in rat skeletal muscle to investigate the hypothesis that structural modifications to...