bifunctional 3'-phosphoadenosine 5'-phosphosulfate synthase 1; PAPS synthase 1; PAPSS 1; sulfurylase kinase 1; SK 1; SK1; includes: sulfate adenylyltransferase; ATP-sulfurylase; sulfate adenylate transferase; SAT; includes: adenylyl-sulfate kinase; 3'-phosphoadenosine-5'-phosphosulfate synthase; APS kinase; adenosine-5'-phosphosulfate 3'-phosphotransferase; adenylylsulfate 3'-phosphotransferase (PAPSS1, ATPSK1, PAPSS)
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Function
- bifunctional enzyme with both ATP sulfurylase & APS kinase activity
- 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),
- 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
- also involved in the biosynthesis of sulfated L-selectin ligands in endothelial cells
- sulfur metabolism; sulfate assimilation
ATP + sulfate = diphosphate + adenylyl sulfate
ATP + adenylyl sulfate = ADP + 3'- phosphoadenylyl sulfate
Inhibition:
- inhibited by chlorate
Structure
- in the N-terminal section; belongs to the APS kinase family
- in the C-terminal section; belongs to the sulfate adenylyltransferase family
Expression
- expressed in testis, pancreas, kidney, thymus, prostate, ovary, small intestine, colon, leukocytes & liver
- also expressed in high endothelial venules (HEV) cells & in cartilage