Solute carrier families 5 and 6-like; solute binding domain
This superfamily includes the solute-binding domain of SLC5 proteins (also called the sodium/glucose cotransporters or solute sodium symporters), SLC6 proteins (also called the sodium- and chloride-dependent neurotransmitter transporters or Na+/Cl--dependent transporters), and nucleobase-cation-symport-1 (NCS1) transporters. SLC5s co-transport Na+ with sugars, amino acids, inorganic ions or vitamins. SLC6s include Na+/Cl--dependent plasma membrane transporters for the monoamine neurotransmitters serotonin, dopamine, and norepinephrine, and the amino acid neurotransmitters GABA and glycine. NCS1s are essential components of salvage pathways for nucleobases and related metabolites; their known substrates include allantoin, uracil, thiamine, and nicotinamide riboside. Members of this superfamily are important in human physiology and disease. They contain a functional core of 10 transmembrane helices (TMs): an inverted structural repeat, TMs1-5 and TMs6-10; TMs numbered to conform to the SLC6 Aquifex aeolicus LeuT.
Comment:based on the structures of Vibrio parahaemolyticus vSGLT (SLC5), Aquifex aeolicus LeuT (SLC6), and the NCS1, Microbacterium liquefaciens Mhp1, bound with Na+, functional studies of Escherichia coli PutP (SLC5) and mammalian NIS (SLC5), and mutational analysis of vSGLT
Structure:2A65: Aquifex aeolicus LeuT (in outward-facing occluded conformation) binds Na+ in one of two sodium-binding sites
Comment:one of two Na+ binding sites in Aquifex aeolicus LeuT, where it is referred to as the Na binding site 2
Jiyao W et al.(2023). "The conserved domain database in 2023.",