Figure 3.

Substrate-induced efflux of [¹⁴C]citrate or [¹⁴C]α-ketoglutarate from proteoliposomes prelabeled by carrier-mediated exchange. [¹⁴C]citrate (0.1 mm) (A and B) or [¹⁴C]α-ketoglutarate (0.1 mM) (C) was added at time 0 to reconstituted liposomes containing 10 mm citrate (A and B) or α-ketoglutarate (C). Where indicated by the arrow, 2 mm nonradioactive α-ketoglutarate or Glu (A), 2 mm nonradioactive oxaloacetate or Asp (B), or 2 mm nonradioactive citrate, cis-aconitate, or trans-aconitate (C) was added. (▪), With no addition; (•), with α-ketoglutarate; (□), with Glu; (▴), with oxaloacetate; (▵), with Asp; (⋄), with citrate; (♦), with cis-aconitate; (○), with trans-aconitate. Transport was stopped by adding pyridoxal 5′-P (see Methods) after the indicated time intervals.