Figure 2. Transport and ATPase activity of ECF–FolT2.

(a) Transport activity of ECF–FolT2 in proteoliposomes loaded with 5 mM of MgATP (circles), 5 mM MgADP (inverted triangles), 5 mM MgAMP–PNP (triangles) or 5 mM Na₂ATP plus 5 mM EDTA (squares). (b) Efflux activity of ECF–FolT2 from proteoliposomes loaded with 5 mM of MgATP, after accumulation of radiolabelled folate for 16 min. At t=16 min, 5 mM of MgATP (circles), 5 mM MgADP (inverted triangles), 5 mM Na₂ATP plus 5 mM EDTA (squares) or 100 μM non-radiolabelled folate (diamonds) was added to the reactions. (c) ATPase activity of ECF–FolT2 reconstituted in proteoliposomes (black bars) and background ATPase activity by empty liposomes (white bars). When indicated, folate was present both in the lumen of the liposomes and in the environment. The error bars show the s.d.'s from three independent measurements.