This domain is found in phosphoadenosine phosphosulfate (PAPS) reductase enzymes or PAPS sulfotransferase. PAPS reductase is part of the adenine nucleotide alpha hydrolases superfamily also including N type ATP PPases and ATP sulphurylases [1]. The enzyme uses thioredoxin as an electron donor for the reduction of PAPS to phospho-adenosine-phosphate (PAP) [1,2]. It is also found in NodP nodulation protein P from Rhizobium which has ATP sulfurylase activity (sulfate adenylate transferase) [3].

1: Crystal structure of phosphoadenylyl sulphate (PAPS) reductase: a new family of adenine nucleotide alpha hydrolases. Savage H, Montoya G, Svensson C, Schwenn JD, Sinning I; Structure 1997;5:895-906. PMID:9261082

2: Reaction mechanism of thioredoxin: 3'-phospho-adenylylsulfate reductase investigated by site-directed mutagenesis. Berendt U, Haverkamp T, Prior A, Schwenn JD; Eur J Biochem 1995;233:347-356. PMID:7588765

3: ATP sulphurylase activity of the nodP and nodQ gene products of Rhizobium meliloti. Schwedock J, Long SR; Nature 1990;348:644-647. PMID:2250719