Cystinosin, lysosomal cystine transporter (CTNS)

Cystinosin is a lysosomal membrane protein encoded by the CTNS gene, functioning as a proton-driven transporter responsible for the efflux of cystine from lysosomes into the cytoplasm[1][2][5]. It consists of seven transmembrane domains and a highly glycosylated N-terminal region. Loss-of-function mutations in this gene cause cystinosis, a rare autosomal recessive lysosomal storage disorder characterized by the accumulation of cystine within lysosomes and subsequent multi-organ pathology, most critically impacting the kidneys[1][6]. Cystinosin’s role also impacts melanosome pH regulation and bone metabolism. The only established pharmacological strategy is cysteamine therapy, which depletes lysosomal cystine by a mechanism independent of restoring CTNS transporter function[1][6].

Other names

CTNS-LSBCTNS_HUMANPQLC4cystinosis

Decreases lysosomal cystine by converting cystine to compounds exportable via intact lysosomal transporters (cysteamine acts as a cystine-depleting agent rather than a direct CTNS modulator)