Figure 1. Illustration of the different structures in the ABC transporter superfamily.
Full structure represents the ABC transporter gene that encodes two TMDs and two NBDs; Half structure represents the ABC transporter gene that encodes one TMD and one NBD; Single structure represents the ABC transporter gene with a single TMD or NBD; ABC2 structure represents the ABC transporter gene with only two NBDs. The families possessing certain structures are listed on the right.