This is a family of integral membrane permeases that are involved in gluconate uptake. E. coli contains several members of this family including GntU Swiss:P46858 a low affinity transporter [1] and GntT Swiss:P39835 a high affinity transporter [2].

1: Gene organization and transcriptional regulation of the gntRKU operon involved in gluconate uptake and catabolism of Escherichia coli. Izu H, Adachi O, Yamada M; J Mol Biol 1997;267:778-793. PMID:9135111

2: Molecular genetic characterization of the Escherichia coli gntT gene of GntI, the main system for gluconate metabolism. Porco A, Peekhaus N, Bausch C, Tong S, Isturiz T, Conway T; J Bacteriol 1997;179:1584-1590. PMID:9045817