1. The Three Stages of Cell Signaling By: Madeline Meyer and Carlos Sanchez ReceptionTransductionResponse

2. Why is this important? Perceive Surroundings Tissue Repair Homeostasis Functioning Immune System

3. RECEPTION

4. G Protein-Coupled Receptors (GPCRs) Cell-surface transmembrane protein, works with G protein, which binds GTP to make energy Signal mol.s = ligands (“link” to another mol. to begin transduction) Widespread functions, therefore widespread structures (all similar)

5. G Protein-Coupled Receptors

6. Receptor Tyrosine Kinases (RTK) Enzymatic activity Kinase catalyzes transfer of phosphate groups Tyrosine kinases catalyze transfer of phosphate group from ATP to amino acid tyrosine on substrate protein *ONE tyrosine kinase complex can activate > 10 transduction pathways* Different from G proteins, which activate only 1 pathway each

7. Evolutionary significance All G proteins are similarly shaped (with vital differences) This means that the G protein likely evolved very early, hence it plays a large role in signal transduction in many distant organisms

8. Transduction

9. Phosphorylation Cascades Protein Kinases- Starts off the process One enzyme phosphorylates another, then another, then another… Protein Phosphatase lead to dephosphorylation

10. Second Messengers- Cyclic AMP Cyclic Adenosine Monophosphate Water Soluble- Spread through diffusion Adenylyl Cyclase & Epinephrine G proteins

12. Benefits of Multistep system Amplification of signal More coordinated and regulated

13. Response

14. Occurs in nucleus or cytoplasm Transcription factors Multiple responses to the same signal Scaffolding proteins