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 used by sulfotransferase). In mammals, PAPS is the sole source of sulfate; APS appears to be only an intermediate in the sulfate-activation pathway (PubMed:7493984). Required for normal biosynthesis of sulfated L-selectin ligands in endothelial cells (By similarity). ATP + H(+) + sulfate = adenosine 5'-phosphosulfate + diphosphate adenosine 5'-phosphosulfate + ATP = 3'-phosphoadenylyl sulfate + ADP + H(+) Sulfur metabolism; sulfate assimilation. Homodimer. Expressed in the neonatal brain and in cartilage. In the N-terminal section; belongs to the APS kinase family. In the C-terminal section; belongs to the sulfate adenylyltransferase family.