Signaling Pathways That Control Gene Expression

Chapter 16 - Signaling Pathways That Control Gene Expression

16.1 Receptor Serine Kinases That Activate Smads

• The transforming growth factor β (TGF-β) family inhibits cell proliferation and regulates development.
• Three types of TGF-β receptors activate Smads.
• Smads interact with regulatory DNA sequences at sites adjacent to those occupied by cell-specific master transcription factors to induce target genes cell-specifically.

TGF-β/Smad Signaling Pathway

• (a) Mature dimeric TGF-β:
  • Shows the mature dimeric form of TGF-β.
• (b) Exterior TGF-β:
  • RIII: A type of TGF-β receptor.
  • RII: Another type of TGF-β receptor that interacts with TGF-β.
  • RI: A third type of TGF-β receptor.
  • 1a & 1b: Initial steps in the pathway.
• Cytosol: The location of several key events.
  • Smad2/3: A type of Smad protein.
    • Contains a Nuclear Localization Signal (NLS).
    • Also contains MH2 and MH1 domains.
  • 3: Smad2/3 becomes phosphorylated (Smad2/3-P).
  • Smad4: Another Smad protein.
    • Also contains MH2 and MH1 domains and NLS.
  • Imp-β: Importin-beta, involved in nuclear import.
  • 10: A phosphatase removes the phosphate group from Smad2/3-P.
• Nucleus: Where transcription regulation occurs.
  • Smad2/3-P: Phosphorylated Smad2/3 enters the nucleus.
  • Smad4: Smad4 also enters the nucleus.
  • Ran: A GTPase involved in nuclear transport.
  • 6: Step involving Ran.
  • STP: Something related to the signaling process.
  • TFE3: A transcription factor.
  • 8: Phosphorylation step (P).
  • Co-activators: Proteins that enhance transcription.
  • Transcription: The process of gene expression.
  • AGACCACGTG PAI-1 JAYAY: DNA sequence.
  • 3-bp spacer: A three base pair spacer in the DNA sequence.
• AWMAGACAGAC: a DNA sequence
• SIN: a protein
• S: a protein
• G: a protein