1. Ionotropic & Metabotropic Receptors Lesson 12

2. Membrane Proteins: Ionophores n Ion Channels n Non-gated l always open n Gated l chemically-gated l electrically-gated l mechanically-gated ~

3. Chemically-Gated Channels n Ligand-Receptor binding n Ligand l neurotransmitters l drugs n Receptor proteins l ligand binds to multiple receptors l receptor subtypes l specificity ~

4. Ligand-Receptors Binding n Binding site l specific point of ligand & receptor n Affinity l attraction l physical & electrical fit n NT or drug binds to receptor l  or  activity of neuron l excite or inhibit n Drugs mimic or block NT message ~

5. Lock & Key Model n Receptor changes shape n Excitation or Inhibition? l Determined by nature of receptor n NOT NT ~ n NT binds to receptor l NT = key l Receptor = lock

6. Receptor Subtypes n Specificity n Same NT l Binds to many receptor subtypes l Produce different effects l EPSP or IPSP n All NT systems l Several subtypes each l Drug side effects ~

7. Receptor A NT n ligand binds to receptor l activation: EPSP or IPSP ~

8. Receptor B Receptor A n Same NT can bind to different -R l different part of NT ~ NT

9. Receptor B Receptor A n Same NT can bind to different -R l different part of NT ~ NT

10. Receptor B Receptor A n Same NT can bind to different -R l different part of NT ~ NT

11. Ionotropic receptors n Ligand-gated channels l Ion channels n NT directly controls channel l fast action l transient ~

12. Metabotropic Receptors n Requires energy l GTP l Neuromodulation n G protein-gated Ion Channels l Receptor indirectly controls channel l relatively fast, but slower than ionotropic ~

13. G protein-gated Ion Channels R G GDP

14. G protein-gated Ion Channels R G GTP

15. G protein-gated Ion Channels R G GTP Pore

16. Metabotropic receptors: 2d messenger systems n 2d messenger systems l Effects relatively slow l long-lasting l Signal amplification n Effects l Control channel l Alter properties of receptors l regulation of gene expression ~

17. 2d Messenger Systems n Signal amplification l 1 NT  activate enzyme  l ATP  1000s cAMP  10,000s  l cAMP  10,000s phosphates ~

18. 2d Messenger Systems Receptor trans- ducer primary effector external signal: nt 2d messenger secondary effector Receptor trans- ducer primary effector external signal: nt 2d messenger secondary effector n External signal l NT = 1st messenger n Membrane-associated components l Receptor l Transducer l Primary effector n Intracellular l 2d messenger l Secondary effector ~

19. 2d Messenger Systems R G GTP GDP * Secondary Effector Primary Effector Enzyme

20. 2d Messenger Systems R G GTP Secondary Effector Primary Effector Enzyme

21. 2d Messenger Systems R G GTP ATP cAMP Secondary Effector Primary Effector Enzyme

22. 2d Messenger Systems R G GTP ATP cAMP P Secondary Effector Primary Effector Enzyme

23. 2d Messenger Systems R G GTP ATP P Pore cAMP Secondary Effector Primary Effector Enzyme