This gene encodes a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such as steroids, bilirubin, hormones, and drugs, into water-soluble, excretable metabolites. This gene is part of a complex locus that encodes several UDP-glucuronosyltransferases. The locus includes thirteen unique alternate first exons followed by four common exons. Four of the alternate first exons are considered pseudogenes. Each of the remaining nine 5' exons may be spliced to the four common exons, resulting in nine proteins with different N-termini and identical SLCtermini. Each first exon encodes the substrate binding site, and is regulated by its own promoter. The preferred substrate of this enzyme is bilirubin, although it also has moderate activity with simple phenols, flavones, and C18 steroids. Mutations in this gene result in Crigler-Najjar syndromes types I and II and in Gilbert syndrome. [provided by RefSeq, Jul 2008]
Function:
UDPGT is of major importance in the conjugation and subsequent elimination of potentially toxic xenobiotics and endogenous compounds. This isoform glucuronidates bilirubin IX-alpha to form both the IX-alpha-C8 and IX-alpha-C12 monoconjugates and diconjugate. Is also able to catalyze the glucuronidation of 17beta-estradiol, 17alpha-ethinylestradiol, 1-hydroxypyrene, 4-methylumbelliferone, 1-naphthol, paranitrophenol, scopoletin, and umbelliferone. Isoform 2 lacks transferase activity but acts as a negative regulator of isoform 1.
DISEASE:
The disease is caused by mutations affecting the gene represented in this entry.The disease may be caused by mutations affecting the gene represented in this entry. The defect has been ascribed to various breast milk substances, but the component or combination of components that is responsible remains unclear. Defects of UGT1A1 are an underlying cause of the prolonged unconjugated hyperbilirubinemia associated with breast milk. One or more components in the milk may trigger the jaundice in infants who have such mutations. Mutations are identical to those detected in patients with Gilbert syndrome, a risk factor of neonatal non-physiologic hyperbilirubinemia and a genetic factor in fasting hyperbilirubinemia.
Similarity:
Belongs to the UDP-glycosyltransferase family. {ECO:0000305}.
SWISS:
P22309
Gene ID:
54658
Database links:
Entrez Gene: 54658 Human
Entrez Gene: 394436 Mouse
Entrez Gene: 24861 Rat
Omim: 191740 Human
SwissProt: P22309 Human
SwissProt: Q63886 Mouse
SwissProt: Q64550 Rat
Unigene: 554822 Human
Unigene: 300095 Mouse
Unigene: 26489 Rat
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