Subcellular distribution of two enzyme systems which degrade 3′-phosphoadenosine 5′-phosphosulfate ("Active sulfate")

1. 1. The subcellular distribution of two enzyme systems which degrade 3′-phosphoadenosine 5′-phosphosulfate (PAPS) ("active sulfate") has been determined. PAPS sulfatase has the wider distribution and accounts for most of the PAPS hydrolyzed. The 3′-phosphoadenosine 5′-phosphate (PAP) thus formed might be available to serve as the requisite coenzyme in phenolic sulfotransferase reactions (detoxification). 2. 2. PAPS-phosphatase activity has a more restricted distribution. It is concentrated in the lighter vesicles of the smooth endoplasmic reticulum (Smooth-4 fraction). It is chiefly present in the soluble portion of this fraction. The adenosine 5′-phosphosulfate (APS) thus formed might be available for conversion back to PAPS as required by the needs of the sulfotransferase systems (lipid, mucopolysaccharide, steroid) also localized in the smooth reticulum.