The donor-binding region of vertebrate UGT proteins. Shown is an alignment of the donor-binding region of the human, chimpanzee, rhesus monkey, baboon, dog, cow, mouse, rat, opossum, chicken, frog, and zebrafish UGT1 constant polypeptides and the corresponding donor-binding region of the human (h), mouse (m), and rat (r) UGT2A constant polypeptides and UGT2B proteins. Residues predicted to interact with the donor UDPGA are highlighted in white letters with black background and marked by red asterisks below. Residues close to the donor are highlighted with turquoise background and are also boxed. Missense mutations in the UGT1A1 that cause human CN-I, CN-II, or Gilbert syndromes are indicated above the alignment. For UGT1, constant polypeptides are shared by multiple UGT1A proteins in each species. For UGT2, individual protein sequence is shown except h2a, m2a, and r2a, which are the human, mouse, and rat UGT2A constant polypeptides, respectively.