Converts adenosine 3'-phosphate 5'-phosphosulfate (PAPS) to adenosine 5'-phosphosulfate (APS) and 3'(2')-phosphoadenosine 5'- phosphate (PAP) to AMP. May regulate the flux of sulfur in the sulfur-activation pathway by converting PAPS to APS (PubMed:10205895) (By similarity). Prevents both the toxicity of PAP on RNA processing enzymes as well as the product inhibition by PAP of sulfate conjugation. Is also able to hydrolyze inositol 1,4-bisphosphate (PubMed:10205895). adenosine 3',5'-bisphosphate + H2O = AMP + phosphate 1D-myo-inositol 1,4-bisphosphate + H2O = 1D-myo-inositol 4-phosphate + phosphate Inhibited by Li(+) (IC(50)=10 millimolar), Na(+) (IC(50)=200 millimolar) and Ca(2+) (IC(50)=0.03 millimolar). Signal transduction; phosphatidylinositol signaling pathway. Very low expression in roots, leaves, stems, flowers and siliques. Substrate preference is 3'-phosphoadenosine 5'-phosphate (PAP) > adenosine 3'-phosphate 5'-phosphosulfate (PAPS)>> inositol 1,4-bisphosphate. No activity observed against 3' or 5'-AMP, inositol monophosphate and fructose-1,6-bisphosphate. Belongs to the inositol monophosphatase superfamily.