Uptake of αMG by intact cells expressing circularly permuted variants of IICBGlc. (A) Wild-type (open circle) and variants with N and C termini in CL1 (open square), CL2 (open triangle up), and CL3 (open triangle down). (B) Wild-type (open circle) and variants with N and C termini in PL1 (solid square), PL2 (solid triangle up), PL3 (solid triangle down), and PL4 (solid diamond). (C) Wild-type (open circle) and PhoA fusion proteins PL1-PhoA (solid square), PL2-PhoA (solid triangle up), and PL3-PhoA (solid triangle down). The uptake reaction was started by the addition of 12 μl of 10 mM [14C]αMG (6,000 dpm/nmol) to 1 ml of the cell suspensions diluted to OD550 = 13 at room temperature, and 100-μl aliquots were withdrawn at the indicated time points, filtered through glass fiber filters, and counted.