Cell Signalling Flashcards
Signaling, besides endocrine, paracrine, and autocrine, what is the fourth type of cell signaling?
Plasma membrane attached proteins
What are the four major attributes (goals) of cellular communication?
Specificity, Amplification, Regulation, and Integration
What is the first step for G protein coupled receptors?
Binding of hormones induces a conformational change in receptor
What does the activated receptor bind to?
G-alpha subunit
What happens to the G-alpha subunit after the activated receptor binds to it?
The G-alpha subunit undergoes a conformational change, triggering the dissociation of GDP
What happens after the GDP leaves the G-alpha subunit?
GTP binds to G-alpha and triggers its dissociation from the G-beta-gamma and the activated receptor
What happens to the activated receptor once the G-alpha dissociates from it?
The hormone (that started it all) dissociates from the receptor
What happens to the newly “freed” GTP-bound G-alpha protein?
It binds to the effector, activating it
What happens when the effector-bound G-alpha protein has its bound-GTP undergo hydrolysis to GDP?
The G-alpha dissociates from the effector and reassociates with G-beta-gamma, becoming the Trimeric Gs protein (with the GDP bound G-alpha subunit)
How does adenylate cyclase become activated?
By the GTP-bound G-alpha protein that binds to the adenylate cyclase (the effector)
What does the activation of adenylate cyclase result in?
Increased release of cAMP
What does cAMP activate Protein Kinase A?
It binds to regulatory subunits and releases the catalytic subunits of Protein Kinase A to do their thing (phosphorylate)
How is the G protein inactivated?
GTP bound to G-(alpha)s is hydrolyzed by an internal GTPase (like a timer)
How is cAMP activity terminated?
by cAMP phosphodiestrase
What are the two diseases associated with the failure to turn off the G protein signal?
Cholera and Whooping Cough (pertussis)
What are two molecules that can activate Protein Kinase C?
DAG and IP3
What is involved in the Nitric Oxide pathway?
Acetylcholine -> ACh GPCR > Phosholipase C > IP3 > Calcium/Calmodulin > NO synthase > NO to NO Receptor > Protein kinase G > smooth muscle relaxation
