Monoamine transporters – putative

The "Monoamine transporters – putative" group refers to a specific subfamily within the Solute Carrier 6 (SLC6) family, also known as the neurotransmitter sodium symporter (NSS) family [32, 38]. This subfamily comprises five members: SLC6A15, SLC6A16, SLC6A17, SLC6A18, and SLC6A19 [38]. Although they are phylogenetically closely related to the classical monoamine transporters (DAT, NET, and SERT), most members of this group have been identified as transporters for neutral amino acids rather than biogenic amines [32, 36]. For instance, SLC6A15 (B0AT2) and SLC6A19 (B0AT1) are primary transporters for branched-chain and other neutral amino acids in the brain and peripheral tissues, respectively [27, 32]. These transporters play critical roles in nutrient absorption, neurotransmitter precursor availability (such as glutamate and GABA precursors), and cellular homeostasis [30, 34]. Genetic variations in these transporters are associated with various conditions, including major depressive disorder (SLC6A15), intellectual disability (SLC6A17), and Hartnup disease (SLC6A19) [27, 34, 36]. While they were historically considered "orphan" transporters, recent drug discovery efforts have identified selective inhibitors, such as JNT-517 for SLC6A19 in the treatment of phenylketonuria, and loratadine and tiagabine as inhibitors for SLC6A15 [45, 46, 50]. Additionally, the plasma membrane monoamine transporter (PMAT, SLC29A4) is sometimes colloquially referred to as a putative monoamine transporter due to its ability to transport biogenic amines despite belonging to the SLC29 family [19, 20].

Other names

SLC6 putative monoamine transporter subfamilySLC6 orphan transportersSLC6A15-19B0AT subfamilyNeutral amino acid transporter subfamily

Sodium-dependent symport of neutral amino acids (e.g., leucine, proline, glutamine) across the plasma membrane or into synaptic vesicles [32, 36, 50].