Arylsulfatase C, Isozyme F (ARSC2)

Arylsulfatase C is a microsomal membrane-bound enzyme. Both forms are X-linked and both escape X inactivation. The 2 genes are probably closely linked and located in the small subtelomeric region of Xp where the other loci that escape inactivation map. Only the placental s form of arylsulfatase C had steroid sulfatase activity and hydrolyzes estrone sulfate, dehydroepiandrosterone sulfate, and cholesterol sulfate. The liver f form had barely detectable activity towards these sterol sulfates. With the artificial substrate 4-methylumbelliferyl sulfate, both forms demonstrated a similar activity, but had different optimum pH. Polyclonal antibodies raised against the placental form reacted specifically against the s and not the f form. The 2 isozymes of arylsulfatase C in humans purified from placenta and liver, respectively, are distinct proteins with different substrate specificity, pH optima, heat lability, and antigenic properties.