To prevent unconjugated bilirubin being deposited in tissues it is bound to albumin (a protein) and then transported in the blood to the liver where it is converted to its conjugated form by an enzyme called glucuronyltransferase (England, 2010; McIntosh and Stenson, 2008).
Glucuronyltransferase, which converts unconjugated bilirubin to conjugated bilirubin, is thought to be less active in the newborn while conversely the enzyme that converts conjugated bilirubin to unconjugated bilirubin in the intestine (beta-glucuronidase) is thought to be more active (Preer and Phillip, 2011).
This entry of bilirubin into liver cells is enabled by an enzyme called glucuronyltransferase
Fogelfeld L, Sarova-Pinchas I, Meytes D, et al: Phosphofructokinase deficiency (Tarui disease) associated with hepatic glucuronyltransferase
deficiency (Gilbert's syndrome): a case and family study.
DLCs, including some PCB congeners, bind to the aryl hydrocarbon receptor (AhR) and activate the hepatic uridine diphosphate glucuronyltransferase
(UDP-GT) enzymes responsible for [T.
Sampeitro M, Lupica L, Perrero L, et al: The expression of uridine diphosphate glucuronyltransferase
gene is a major determinant of bilirubin level in heterozygous [beta] thalassemia and in G6PD deficiency.
Gilbert syndrome is an inborn error of bilirubin conjugation caused by mutations in the conjugating enzyme uridine diphosphate glucuronyltransferase
4] metabolism by the induced glucuronyltransferase
Anti-microsomal antibodies targeting P450IA2 and P450IIIAl isoenzymes have also been reported in idiosyncratic liver injuries associated with dihydralazine and aromatic anticonvulsants, as well as anti-LKM3 antibodies directed against uridine diphosphate glucuronyltransferase
(UDPGT) enzymes [24-26].
DHMA and HMMA can be further conjugated by uridine diphosphate glucuronyltransferases
(UGTs) to DHMA 3-glucuronide, DHMA 4-glucuronide, and HMMA glucuronide or by sulfotransferases to DHMA 3-sulfate, DHMA 4-sulfate, and HMMA sulfate.