This NCS1 subfamily includes Microbacterium liquefaciens Mhp1, and various uncharacterized NCS1s. Mhp1 mediates the uptake of indolyl methyl- and benzyl-hydantoins as part of a metabolic salvage pathway for their conversion to amino acids. Mhp1 has 12 transmembrane (TM) helices (an inverted topology repeat: TMs1-5 and TMs6-10, and TMs11-12; TMs numbered to conform to the Solute carrier 6 (SLC6) family Aquifex aeolicus LeuT). NCS1s are essential components of salvage pathways for nucleobases and related metabolites; their other known substrates include allantoin, uracil, thiamine, and nicotinamide riboside. NCS1s belong to a superfamily which also contains the solute carrier 5 family sodium/glucose transporters (SLC5s), and SLC6 neurotransmitter transporters.
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
Comment:one of two Na+ binding sites in Aquifex aeolicus LeuT, where it is referred to as the Na binding site 2
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