Bifunctional 3'-phosphoadenosine 5'-phosphosulfate synthase 2 (PAPSS2)

Bifunctional enzyme with both ATP sulfurylase and APS kinase activity, which mediates two steps in the sulfate activation pathway. The first step is the transfer of a sulfate group to ATP to yield adenosine 5'-phosphosulfate (APS), and the second step is the transfer of a phosphate group from ATP to APS yielding 3'-phosphoadenylylsulfate (PAPS: activated sulfate donor employed by sulfotransferase).

In mammals, PAPS is the only source of sulfate; APS appears to be only an intermediate in the sulfate- activation pathway. May have a essential role in skeletogenesis during postnatal growth (By similarity).