Characterization of Plasma Membrane Proteins in Mammalian Kidney: II. The Binding of Organic Mercurials to Rat Kidney Plasma Membrane Proteins in vivo

Abstract

Abstract The binding of organic mercurial compounds to the proteins of kidney plasma membrane preparations has been examined following the administration in vivo of organic mercurial compounds labeled with 203Hg. When the kidney cells are fractionated, plasma membrane radioactivity is lower than radioactivity in the cytoplasm. The radioactivity appears to be bound to membrane protein and experiments with 14C-labeled p-chloromercuribenzoate and 3H-labeled chlormerodrin indicate that the binding 2 hours after administration is mostly that of free mercury. When plasma membranes are solubilized and chromatographed on 6% agarose gel, two major protein peaks are eluted. p-Chloromercuribenzoate label is localized primarily in the high molecular weight proteins of the initial void volume peak. Chlormerodrin, a compound with diuretic activity in the kidney, is distributed fairly evenly in the protein fractions of both column peaks. Electrophoretic data, however, suggest heterogeneity of the protein labeling by chlormerodrin. Sodium-potassium-dependent ATPase activity is found in several fractions of the first peak eluted from the agarose gel column. When ouabain, a known inhibitor of the ATPase system, is administered in vivo, it depresses the chlormerodrin radioactivity of the first peak.