The function of Ensembl gene identifier ENSG00000040531 (CTNS, cystinosin, lysosomal cystine transporter) is as follows. Cystine/H(+) symporter that mediates export of cystine, the oxidized dimer of cysteine, from lysosomes (PubMed:11689434, PubMed:15128704, PubMed:18337546, PubMed:22232659, PubMed:29467429, PubMed:33208952, PubMed:36113465). Plays an important role in melanin synthesis by catalyzing cystine export from melanosomes, possibly by inhibiting pheomelanin synthesis (PubMed:22649030). 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 (PubMed:36113465). Also involved in small GTPase-regulated vesicle trafficking and lysosomal localization of LAMP2A, independently of cystine transporter activity (By similarity). {ECO:0000250|UniProtKB:P57757, ECO:0000269|PubMed:11689434, ECO:0000269|PubMed:15128704, ECO:0000269|PubMed:18337546, ECO:0000269|PubMed:22232659, ECO:0000269|PubMed:22649030, ECO:0000269|PubMed:29467429, ECO:0000269|PubMed:33208952, ECO:0000269|PubMed:36113465}.