Iduronate 2-sulfatase (IDS) is required for the lysosomal degradation of heparan sulfate and dermatan sulfate. Mutations causing IDS deficiency in humans result in the lysosomal storage of these glycosaminoglycans and Hunter syndrome,an X chromosome-linked disease. An internal proteolytic cleavage occurs to produce the mature IDS present in human liver shown to contain a 42 kDa polypeptide N-terminal to a 14 kDa polypeptide..