Lysosomal amino acid transporter 1 homolog (SLC66A1)

Lysosomal amino acid transporter 1 homolog (SLC66A1, also known as PQLC2 or LAAT-1) is a lysosomal transmembrane protein that functions as a pH-dependent transporter to export cationic amino acids—specifically arginine, lysine, and histidine—from the lysosomal lumen to the cytosol[2][5][7]. This activity is essential for maintaining intracellular amino acid homeostasis and supporting cellular metabolism[2][4][6]. In addition to its transporter activity, SLC66A1 also acts as a sensor—a “transceptor”—by detecting lysosomal cationic amino acid depletion and subsequently recruiting the C9orf72-SMCR8-WDR41 protein complex to the lysosomal surface[1][3][4][8]. This recruitment is critical for lysosome-based signaling, including impacts on mTORC1 activity and potentially on neuronal cell homeostasis[1][4]. Loss-of-function mutations in SLC66A1 cause inherited retinal disorders such as autosomal recessive retinitis pigmentosa, while dysregulation (such as upregulation in cancers) is associated with tumorigenesis and poor prognosis in gastric cancer[6]. There are currently no established drugs that directly target SLC66A1, and no validated biomarkers or specific safety concerns have been described in the context of therapy.

Other names

PQLC2LAAT-1LAAT1PQ-loop repeat-containing protein 2FLJ20320PQ loop repeat containing 2solute carrier family 66 member 1