A Protein O-glucosyltransferase activity of wild-type (WT) or D233E mutant POGLUT1 protein toward human factor IX EGF repeat (hFIX-EGF). Wild-type shows higher O-glucosyltransferase activity than D233E, and this activity is dependent on the concentration of the acceptor substrate hFIX-EGF repeat (left) and on the concentration of donor substrate UDP-glucose (UDP-Glc) (right). Values indicate mean ± SEM from three independent assays. 