“…Variants associated with disease also have been found lining the substrate binding clefts of NDST-1, 2-OST-1, and 6-OST-1 (Najmabadi et al, 2011;Reuter et al, 2014;Schneeberger et al, 2020;Tornberg et al, 2011). Disease associated variants are also found clustered within the highly conserved 3ʹSB and 5ʹPSB strand-loop-helix motifs associated with PAPS and acceptor substrate binding (Reuter et al, 2014;Schneeberger et al, 2020;Tibbs et al, 2018). One of the variants for NDST-1, involves the proposed catalytic base, while the R189S of 2-OST involves the residue proposed to dictate specificity for IdoA over GluA (Reuter et al, 2014;Schneeberger et al, 2020).…”