This group includes ribose uptake protein RbsU and similar proteins. RbsU is encoded on the rbsUDK gene cluster, which encodes proteins involved in ribose uptake and phosphorylation. RbsR has been annotated as the repressor of the rbsUDK operon, based on its homology with RbsR repressors. RbsU belongs to the glucose/ribose porter (GRP) family (TC 2.A.7.5) and probably functions by H(+) symport. GRP family proteins have a distinctive topology: 10 putative transmembrane (TM) alpha-helical spanning domains per polypeptide chain, which apparently arose by intragenic duplication of an element encoding a primordial five-TM polypeptide. The GRP family belongs to the Drug/Metabolite Transporter (DMT) superfamily (TC 2.A.7).
Jiyao W et al.(2023). "The conserved domain database in 2023.",