hepatic metabolism (bilirubin)
Last reviewed 01/2018
Bilirubin is taken up into hepatocytes from blood by a carrier protein. It is bound intracellularly to special Y and Z proteins.
The compound UDP glucuronic acid is formed from ADP, glucose and UTP. It reacts with bilirubin under the influence of the enzyme glucuronyl transferse to form:
- mainly bilirubin diglucuronide
- minimal bilirubin monoglucuronide
- UDP
The glucuronide conjugated form of bilirubin is water soluble and hence more suitable for excretion into bile. Excretion occurs into the bile canaliculus by carrier-mediated transport.
Disorders of bilirubin take-up or conjugation can lead to hepatic jaundice.