Partial Purification and Characterization of the Phosphate Transporter from Bovine Heart Mitochondria

Abstract

A highly active phosphate transporter was extracted with octylglucoside from bovine heart submitochondrial particles that were first partially depleted of other membrane components. It was then partially purified by ammonium sulfate fractionation. After reconstitution of the transporter into liposomes prepared with a crude mixture of soybean phospholipids, the Pi/OH exchange, but not the Pi/Pi exchange, was stimulated three- to fourfold by valinomycin and nigericin in the presence of K+. Both Pi/OH and Pi/Pi exchange activities were sensitive to mercurials and other SH reagents. The rutamycin-sensitive ATPase complex from mitochondria was reconstituted together with the phosphate transporter and adenine nucleotide transporter into liposomes. After inhibition of externally located ATPase, the hydrolysis of ATP was sensitive to atractyloside and mersalyl.