1. One second messenger can do lots of different things… p. 888

2. Other second messengers—DAG and IP3 synthesized from membrane phospholipids 20-38, 889

3. Hormone binding activates phospholipase C (similar to G-protein activating adenylyl cyclase) >creates IP3 and DAG >IP3 opens up Calcium from ER >protein kinase C reacts to calcium by moving to membrane- activated by DAG >increase in intracellular Ca++ causes p.m. calcium channel to open 20-39, 890

4. An increase in intracellular calcium can do lots of things too…

5. View Animation

6. And now a totally different kind of signaling molecule- Nitric Oxide (gas)

7. Requires NADPH, calcium, calmodulin, and oxygen

8. Heme in the binding pocket of NOS

10. Learning and memory in Aplysia 21-51, 960 Long-term and short-term memory requires NMDA receptors Long-term requires protein synthesis (but not short-term) One of the proteins synthesized is N-Cam-a cell adhesion molecule (studied by Dr. Q. Liu)

11. NO in penile erection >autonomic neuron of pelvic plexus- innervates penile blood vessels which supply corpora cavernosa (erectile tissue of penis) >stimulate this nerve-, release NO, stimulates guanynyl cylase-make cGMP, blood vessels relax-cause erection in mice >stimulate this nerve in presence of NOS inhibitor-no erection >erection goes away when cGMP destroyed by enzyme cGMP phosphodiesterase type V

12. >10% of human males are impotent- VIAGRA >VIAGRA inhibits cGMP phosphodiesterase type V which is the prominent isoform in corpus cavernosa (so not ALL of your blood vessels relax)