Neutral amino acid transporter A (ASCT1) (ASCT1)

Neutral amino acid transporter A (ASCT1), encoded by the SLC1A4 gene, is a sodium-dependent amino acid exchanger primarily expressed in astrocytes and other glial cells within the central nervous system (UniProt P43007). It facilitates the obligatory exchange of small neutral amino acids, including L-serine, L-alanine, L-cysteine, and L-threonine, playing a pivotal role in the "serine shuttle" that maintains brain amino acid homeostasis (Kaplan et al., 2018). ASCT1 is particularly significant for regulating the availability of L-serine, which serves as a precursor for D-serine, a critical co-agonist for N-methyl-D-aspartate (NMDA) receptors involved in synaptic plasticity and memory (Foster et al., 2018). Mutations in the SLC1A4 gene are linked to a severe neurodevelopmental disorder known as spastic tetraplegia, thin corpus callosum, and progressive microcephaly (SPATCCM), highlighting its essential role in brain development (Srour et al., 2015). While no drugs are currently approved specifically to target ASCT1, L-serine supplementation is used to manage deficiency symptoms, and experimental small-molecule inhibitors like phenylglycine derivatives and alkoxy hydroxy-pyrrolidine carboxylic acids (AHPCs) are being investigated for their potential to modulate NMDA receptor activity in psychiatric and neurodegenerative conditions (Molecules 2024). Beyond the CNS, ASCT1 is expressed in peripheral tissues like the liver and pancreas, where it contributes to systemic amino acid balance and has been implicated in the progression of certain cancers such as hepatocellular carcinoma (Protein Atlas). The transporter also exhibits a thermodynamically uncoupled chloride conductance, which may influence cellular excitability and osmotic balance (Zerangue & Kavanaugh, 1996).

Other names

SLC1A4Alanine/serine/cysteine/threonine transporter 1SATTASCT-1Solute carrier family 1 member 4Neutral amino acid transporter A

Substrate replacement therapy (L-serine) and competitive inhibition of sodium-dependent neutral amino acid exchange.