YCF1-encoded 73As(GS)3 accumulation in vacuoles of S. cerevisiae. As(GS)3 accumulation was assayed in the plasma membrane-enriched (PM) and vacuolar membrane-enriched (VM) fractions from cells of DTY165 or DTY167. 73As(GS)3 was prepared by mixing 0.1 mM Na273AsO2 and 0.4 mM GSH. Accumulation was assayed with 5 mM MgCl2 and 10 mM ATP, unless otherwise noted. Curves: (□), DTY165 VM; (○), DTY165 VM - ATP; (■), DTY165 VM - GSH; (⋄), DTY165 PM; (▵), DTY167 VM; (●), DTY167 PM. (Inset) Membranes from strains DTY165 and DTY167 fractionated by sucrose density gradient centrifugation were analyzed by immunoblotting with antibody against the plasma membrane Pma1p or the vacuolar membrane Pho8p. The arrows indicate the predicted position of Pma1p and Pho8p estimated from the migration of proteins of known molecular mass.