ZIFL family sequence signatures. (A) Alignment of ZIFL and MFS_1 signatures present in the cytoplasmic loop between TM2 and TM3 (MFS signature) and in TM5 (antiporter signature). (B) ZIFL specific signature not found in general MFS_1 proteins. The Cys motif C-[PS]-G-C is observed in the N-terminal cytoplasmic loop; the His motif [PQ]-E-[TS]-[LI]-H-x-[HKLRD] is in the cytoplasmic loop between TM6 and TM7, before the beginning of the variable region (in black); the [RK]-x(2)-G-P-[IV]-x(3)-R motif is in the cytoplasmic loop between TM8 and TM9. The overall transmembrane topology of the ZIFL proteins is schematically shown.