Billy Rubin Pathway Tutorial

Importance of the Billy Rubin Pathway

• Excess Billy Rubin in blood causes jaundice (yellowing of skin)
• Understanding the pathway aids in diagnosing related diseases

Overview of Billy Rubin

• Product of heme catabolism: Breakdown of heme found in red blood cells
• Source of Billy Rubin: Old red blood cells are engulfed by macrophages to initiate heme catabolism

Breakdown of Hemoglobin

• Hemoglobin is composed of:
  • Four subunits (two alpha and two beta)
  • Each subunit has a protein element (globin) and a porphyrin ion complex (heme)
• Process:
  1. Red blood cell is broken down by macrophages
  2. Globin is recycled; heme is dissociated
  3. Heme is transformed into a porphyrin ring
• Porphyrin ring structure: Complex carbon ring with nitrogen elements coordinating with iron

Formation of Billy Rubin

• Porphyrin ring opens up to produce Billy Rubin
  • Characteristics: Bright yellow, toxic molecule
• Significance: Needs to be removed from the body due to toxicity

Transport of Billy Rubin

• Solubility: Not very water-soluble
• Carrier protein: Billy Rubin is attached to albumin for transport in blood
• Destination: Carries Billy Rubin to the liver

Processing in the Liver

• Enzyme involved: UDP glucuronyl transferase
  • Attaches glucuronic acid to Billy Rubin
  • Converts it from unconjugated to conjugated Billy Rubin (less toxic, more water-soluble)

Excretion Process

• Excretion: Conjugated Billy Rubin is excreted into bile and then into intestines
• Bacterial action in intestines: Converts Billy Rubin to stercobilin (precursor to stool color)
  • Stercobilin gives feces its brown color
• Urobilinogen: Some stercobilin is absorbed back into the blood
  • Can be converted to urobilin via oxidation
  • Urobilin is excreted in urine, giving it a yellow color

Future Topics

• Next video: Metabolism of Billy Rubin in the liver and diseases associated with dysfunction in this process

Resources

• For more tutorials and PDFs, visit: www.hhandwritten tutorial.com