In the second step of PAPS biosynthesis, adenylyl sulfate (APS) is phosphorylated to 3'-phosphoadenylyl sulfate (PAPS), catalyzed by the APS kinase domains of the bifunctional enzymes PAPS synthases 1 and 2 (PAPSS1 and 2). PAPSS2 is essential for the sulfation of glycosaminoglycan chains of proteoglycans, a necessary post-translational modification. Defective PAPSS2 results in undersulfation of proteoglycans which causes spondyloepimetaphyseal dysplasia Pakistani type (SEMD-PA; MIM:612847), a bone disease characterized by epiphyseal dysplasia with mild metaphyseal abnormalities. Mutations resulting in SEMD-PA include S438*, T48R and R329* (Ahmad et al. 1998, ul Haque et al. 1998, Noordam et al. 2009).
Venkatachalam, KV, Akita, H, Strott, CA
Girard, JP, Baekkevold, ES, Amalric, F
Superti-Furga, A, Krakow, D, Ahmad, W, Cohn, DH, Rusiniak, ME, Haque, S, Abbas, H, King, LM, Ahmad, M, Swank, RT, ul Haque, MF, Cantor, RM
adenylylsulfate kinase activity of PAPSS1,2 [cytosol]
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