G-Protein

1. By: Khuram aziz Cell signaling: Communication Between Cells and Their Environment Study hard and stay focused on your educational goals. But always have a backup plan! Remember: while chance favors the prepared mind, you can’t always be where the lighting strikes. Overview of intracellular signaling: Initiation and responses

6. Fig 15.3 The G Protein Cycle

11. Ras Activation and the MAP Kinase Cascade Raf-1 (Map kinase kinase kinase) MEK (MAP kinase kinase) ERK (MAP kinase) Tyrosine Kinases, G-Protein coupled receptors Nuclear regulatory proteins Cytoplasmic substrates See Fig. 15.2

12. What does Ras interact with? Raf

15. The regulation of G proteins. Fig. 15.12

22. Take home message #2 Hydrolysis is the turn-off signal that induces heterotrimeric G protein  subunits (G  ) to disengage their effectors. Note change in structure of GTP versus GDP bound G protein

23. Why do we need GEFs?

25. Do you remember everything from yesterday’s lecture? If you say yes, you get a donut! If not, then you need to pay attention to the CREB story. Fact: CREB: cAMP response element binding protein. Binds to DNA at the CRE (cAMP Response Element) and activates transcription.

28. cAMP is generated from ATP by an enzyme: adenylyl cyclase. AC is regulated by G proteins

29. cAMP activates one or more kinases. What are phosphatases?

30. Activation of cAMP and Protein Kinase A also play major roles in response of liver to glucagon or epinephrine. Figure 15.7

32. Regulation of PIP2 and PIP3 Synthesis Green arrows denote stimulatory effects; blue arrows denote synthetic pathways; red denotes inhibitory effect. Feedback inhibitory loop (1). Cross-talk between receptor signaling pathways (2). Feed-forward loop (3).