Adenosine 5′-phosphosulfate (APS)-sulfatase splits sulfate from APS, the direct precursor of 3t́-phosphoadenosine 5′-phosphosulfate (PAPS) "active sulfate". The properties and sub-cellular distribution of APS-sulfatase activity are described in pig kidney cortex. The evidence is consistent with the existence of two species of APS-sulfatases. One enzyme species has an acid and the other a neutral pH optimum. The two differ in their electrophoretic distribution patterns. Activities are concentrated in the vesicles of the smooth endoplasmic reticulum (smooth-4 fraction), in lysosomes, and in the nuclear fraction. Km values indicate a high affinity of these enzymes for APS. APS-sulfatases were also studied in the human and in the rat. The position of these APS-sulfatases in the pathways of sulfate metabolism suggests that they may play an important role in governing sulfate conjugation from PAPS.
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