Extracellularly applied Br-TITU inhibits the Na+/K+ pump by interacting with Tryptophan/s at the entrance to the cation sites

G. A. YUDOWSKI; R. M. GONZÁLEZ-LEBRERO; M. BAR SHIMON; R. C. ROSSI; P. J. GARRAHAN; S. J. D. KARLISH; L. A. BEAUGÉ

ANN. N. Y. ACADEMY SCIEN.

NYAS

Año: 2003 vol. 986 p. 287 - 289

1749-6632

Aryl isothiouronium derivatives, among them Br-TITU, were designed as molecular probes for the cation binding sites of the Na(+),K(+) pump. Previous work showed that Br-TITU binds to renal Na(+),K(+)-ATPase with two different affinities: <1mM on the inside and around 50 mM, presumably on the outside. Here, we describe properties and kinetic characteristics of Br-TITU as a cation antagonist at the extracellular surface of the Na(+),K(+)-ATPase.