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← Lactase TATA Box

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Showing Revision 1 created 09/27/2013 by Cogi-Admin.

  1. Okay kids, it does not get much better than this.
  2. I hope you didn't think I was leading you on
  3. because I was not joking about this tata box. The
  4. t-a-t-a-a-a sequence, otherwise known as the tata box, is a
  5. real thing, and it's also real in the lactase gene.
  6. Here we have the plus one transcription start sign, the
  7. lactase gene That's why I started capitalizing the letters. In
  8. green here, we have the ATG, which would be transcribed,
  9. right, to the AUG in the mRNA. This would be where translation would start for
  10. the lactase coding region, and we'd get our
  11. protein. But how does this transcript even start?
  12. We need this tata sequence in front. This consensus tata squence is a core piece
  13. of the promoter region, of the lactase gene.
  14. Without this TATA region, the correct proteins can't
  15. bind and facilitate the initiation of transcription
  16. which begins right here. Everything that happens for
  17. transcription depends on sequences like this TATA sequence
  18. in the promoter region. Now what you're about
  19. to hear is not made up. It's not
  20. hypothetical. This is reality. In the lactase gene,
  21. if we zoom out, right, we'll see that this tata region is about minus 30, right.
  22. It's 30 base pairs, 30 letters in front of
  23. the transcription initiation site for the lactase gene. And
  24. if we zoom out and look at the whole
  25. chromosome where the lactase gene is sitting, We can
  26. put this in context. The TATA-box in this sense
  27. is right next to the transcription start site. It
  28. turns out that some people in the human population
  29. have a letter difference, a letter change, in the non-coding
  30. region, in front of the lactase gene,
  31. that significantly affects the expression of lactase. Its
  32. own transcription And the amazing thing is
  33. that this letter, this single letter variation in
  34. humans, that affects transcription of the lactase
  35. gene, is more than 20,000 letters, or base
  36. pairs away from the transcription initiation site. This
  37. is not just like that tata region, right?
  38. Minus 30 in front. We are 20,000 letters away and we're
  39. effecting transcription right here. Now, that's going to take some explaining.