PAPSS2 (3'-Phosphoadenosine 5'-Phosphosulfate Synthase 2): PAPSS2 is essential for the biosynthesis of PAPS (3'-phosphoadenosine 5'-phosphosulfate), a key sulphate donor in various sulphation reactions. It plays an important role in the metabolism of hormones, drugs, and other molecules. Mutations in PAPSS2 can lead to disorders such as spondyloepimetaphyseal dysplasia, highlighting its role in skeletal development.