Signal Transduction

Principles Module 21


  • Describe the role of phosphorylation in signal transduction
  • Discuss signal amplification
  • Identify several second messenger molecules and their functions
  • Describe some typical results of signal transduction in the cell

Key points

  • Many signal transduction chains employ protein phosphorylation
    • kinases are enzymes that attach a phosphate to a substrate
    • phosphatases are enzymes that remove phosphates
  • Phosphorylation state changes the activity of a protein
  • Second messengers connect receptors to kinase cascades
  • Cells amplify signals through signal transduction cascades (Fig. 4)
  • Signal transduction chains result in cellular responses
    • changes in gene expression
    • changes in protein activity or degradation
    • passage through the cell cycle and into cell division

In-class activities

  • Review for Friday’s exam, ask any questions for clarification