CTNS

Cystine/H(+) symporter that mediates export of cystine, the oxidized dimer of cysteine, from lysosomes. Plays an important role in melanin synthesis by catalyzing cystine export from melanosomes, possibly by inhibiting pheomelanin synthesis. In addition to cystine export, also acts as a positive regulator of mTORC1 signaling in kidney proximal tubular cells, via interactions with components of the v-ATPase and Ragulator complexes. Also involved in small GTPase-regulated vesicle trafficking and lysosomal localization of LAMP2A, independently of cystine transporter activity (By similarity)..

Function from UniProtKB (O60931), read 2026-09-23. CC BY 4.0.