Alanine-serine-cysteine transporter (ASCT)

The alanine-serine-cysteine transporters (ASCT) generally refer to a family of neutral amino acid transporters, most notably ASCT1 (SLC1A4) and ASCT2 (SLC1A5) in humans. These are well-characterized membrane transport proteins involved in amino acid exchange, with important roles in physiology and disease. They belong to the SLC1 family and are localized to the plasma membrane of various tissues. They catalyze the Na⁺-dependent or Na⁺-independent exchange of small neutral amino acids like alanine, serine, and, in some contexts, cysteine and threonine. ASCT2's main physiological role is glutamine transport, which is crucial for cell proliferation, particularly in cancer, while ASCT1 is more dominant in the central nervous system for serine and glycine regulation. Both are considered therapeutic targets, with ASCT2 being actively pursued for anticancer strategies. Although the term 'Alanine-serine-cysteine transporter' is generic and accurate, the actual substrate specificity for 'cysteine' is debatable, with substrate selectivity leaning towards alanine, serine, threonine, and glutamine. Another related transporter, Asc-1 (SLC7A10), is sometimes referred to as 'alanine-serine-cysteine-1' and is prominent in CNS glycine/D-serine regulation. Dysfunction or blockade of these transporters can lead to significant neurological and metabolic consequences.

Other names

Alanine-serine-cysteine transporter 1SLC1A4ASCT1Alanine-serine-cysteine transporter 2SLC1A5ASCT2

Competitive inhibition of amino acid transport: Many drugs or research tools act by blocking substrate binding or exchange. Disruption of glutamine uptake impairs cancer cell growth by metabolic starvation.