2. Lecture 4 Outline (Ch. 9) I.Cell Signaling Overview II.Signal Transduction III. General Cell Responses IV. Reception in Detail V.Transduction in Detail VI. Exam Review

3. Cell Signaling = Signal Transduction Signal Transduction – receiving a signal & relaying the response

4. Reception Transduction Response Receptor Relay molecules Signaling molecule Activation of cellular response 1 2 3 Signal Transduction Cell phone rings You listen to your friend You drive somewhere Response variable

5. Sending the Signal

6. Reception – receptors for hydrophilic molecules Signal called a ligand

7. Reception – receptors for hydrophobic molecules

8. Transduction – relay the signal Phosphorylation: adding a phosphate group Used to activate proteins already in the cell

9. Signaling molecule Receptor Activated relay molecule Inactive protein kinase 1 Active protein kinase 1 Inactive protein kinase 2 ATP ADP Active protein kinase 2 P P PP Inactive protein kinase 3 ATP ADP Active protein kinase 3 P P PP i ATP ADP P Active protein PP P i Inactive protein Cellular response Phosphorylation cascade i hydrophilic signals Receptor alerts molecules inside the cell = phosphorylation Transduction – relay the signal

10. First messenger G protein Adenylyl cyclase GTP ATP cAMP Second messenger Protein kinase A G protein-coupled receptor Cellular responses Transduction – relay the signal Or use second messengers = small molecules inside cell examples: cAMP, ATP, Ca++

11. Interdigital tissue 1 mm Response – cell does something

12. protein (active) Inhibits activity Mitochondrion Receptor for death- signaling molecule Inactive proteins (a) No death signal Response – ex. No death signal, cell lives

13. (b) Death signal Death- signaling molecule (inactive) Cell forms blebs Active Activation cascade Other proteases Nucleases Response – ex. Death signal, cell undergoes apoptosis

14. Growth factor Receptor Phosphorylation cascade Reception Transduction Active transcription factor Response P Inactive transcription factor CYTOPLASM DNA NUCLEUS mRNA Gene Signal transduction = reception, transduction, response

15. Lecture 4 Summary 1. Cell Signaling Overview (Ch. 9) -Reception -Transduction -Response 2. Sending the signal (Ch. 9) -Contact, paracrine, endocrine, synaptic -Hydrophilic vs. hydrophobic ligands 3. Signal Reception (Ch. 9) 4. Transduction (Ch. 9) -Phosphorylation/dephosphorylation -Cascades/amplification -Second messengers 5. Cellular Response (Ch. 9)

16. Exam I Review Actually write down info – I may collect some of this…. For each of the following images, discuss with your partner briefly and agree what the image is showing. THEN, each person write their own question about this topic – avoid simple questions such as “what is this image” in favor of concepts about the image. THEN, exchange questions with your neighbor and solve/answer. Discuss your answers and grade each other. I may call on specific teams to provide examples of their questions (remember, if I like them, they may appear on the test!)

23. Photosynthesis: (Endergonic)

25. Active protein kinase 1 Inactive protein kinase 2 ATP ADP Active protein kinase 2 P P PP i

26. 1 2 3