4.17.20 ENCOUNTERS

This week mentioned different types of cell signaling, however the G-protein cascade is a major concept that has been discussed outside of cellular biology class. In biochemistry we talked about the cascade system in terms of reactions vs. studying the pathway. I now am able to decipher that 7TM domain stand for 7 Trans-Membrane proteins due to the 7 connected alpha helices imbedded in the membrane. I know that the B-adrenergic receptors were 7TM receptors found in the muscle or liver cells, and that it was a tetramer composed of an alpha, beta and gamma subunit. The inactive state was the tetramer, however after exchanging a GDP for GTP, the alpha subunit dissociates from the other subunits and becomes active. Further conversation in cellular biology allowed me to learn that the beta-gamma complex is active as well and binds to its own target enzyme or channel, whereas in Biochemistry the alpha subunit was the only part studied in great detail. Furthermore, the cellular biology lecture allowed me to see where exactly cyclic AMP bound protein kinase A, regions on the two regulatory subunits, something seemingly ignored in Biochemistry. The topic of regulation seemed to match the most between the two courses, since there were different levels that the cascade must be “shut-down” at.