Course/Module 4/Lesson 7

Lesson 7

The Chemistry of Pheomelanin

The Compromised Path

⏱ 0:43
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Audio Narration

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"Now we need to talk about what happens when the MC1R switch doesn't work. This isn't about judgment — it's about understanding a different chemistry."
Key Terms
  • Cysteine: A sulfur-containing amino acid that intercepts melanin production.
  • Benzothiazine: The unstable sulfur-based units that make up pheomelanin.
  • Glutathione: The body's 'master antioxidant' that gets depleted by pheomelanin.

When the MC1R switch is 'broken' or loss-of-function, the dopaquinone we talked about earlier gets intercepted by a molecule called cysteine. Cysteine contains sulfur. Instead of building the strong eumelanin shield, the cell starts building pheomelanin. This pigment is yellow-to-red and structurally unstable. But here is the critical part: to build pheomelanin, the cell has to use up its glutathione — the body's most important chemical for cleaning toxins. This means making pheomelanin actually lowers your body's overall antioxidant reserves.

DOPAQUINONEEUMELANINPHEOMELANINTHE PATHWAY FORK

Key Takeaways

  • ◈ Pheomelanin is sulfur-based, unlike eumelanin.
  • ◈ Its synthesis actively depletes the body's antioxidant supply.
  • ◈ This is the default setting when the MC1R gene is mutated.
Collapse Check — Reflection

Apply Your Intelligence

If a shield costs you more to build than it saves, is it still a winning strategy for the cell?

Next: It gets even more interesting. Pheomelanin doesn't just wait for the sun to cause trouble.
Module Overview