This family consists of several bacterial branched-chain amino acid transport proteins which are responsible for the transport of leucine, isoleucine and valine via proton motive force [1].

1: Cloning and characterization of brnQ, a gene encoding a low-affinity, branched-chain amino acid carrier in Lactobacillus delbruckii subsp. lactis DSM7290. Stucky K, Hagting A, Klein JR, Matern H, Henrich B, Konings WN, Plapp R; Mol Gen Genet 1995;249:682-690. PMID:8544834