The human arylsulfatase-C isoenzymes: two distinct genes that escape from X inactivation.

Arylsulfatase C is a microsomal membrane-bound enzyme previously thought to be the same as steroid sulfatase, the only X-linked enzyme known to escape from X inactivation in man. We had shown that arylsulfatase C actually consists of two biochemically distinct isozymes, s and f. Only the s form has steroid sulfatase activity. The f and s forms were thought to be related through posttranslational or posttranscriptional modification of the same …