Cystinosis, Nephropathic (CTNS)

CTNS encodes a seven-transmembrane domain protein that functions to transport cystine out of lysosomes. Its activity is driven by the H+ electrochemical gradient of the lysosomal membrane. Mutations in this gene cause cystinosis, a lysosomal storage disorder. Alternative splicing results in multiple transcript variants.

CTNS encodes an integral membrane protein, which they designated cystinosin, that has features of a lysosomal membrane protein. CTNS, a putative cystine transporter, contains 367 amino acids and 7 transmembrane domains. A 2.7-kb transcript of the CTNS gene was strongly expressed in pancreas, kidney (mature and fetal), skeletal muscle, to a lesser extent in placenta and heart, and weakly in lung and liver.