This region in the nucleoside transporter proteins are responsible for determining nucleoside specificity in the human CNT1 and CNT2 proteins. In the FeoB proteins, which are believed to be Fe2+ transporters, it includes the membrane pore region, so the function of this region is likely to be more general than just nucleoside specificity. This family may represent the pore and gate, with a wide potential range of specificity. Hence its name 'Gate'.
Jiyao W et al.(2023). "The conserved domain database in 2023.",