Receptor mechanism II Flashcards
How many proteins is a G protein receptor made up of?
1 protein
How many transmembrane domains and agonist binding site do G protein receptors have?
7 transmembrane domains
1 agonist binding site
What are G proteins a family of and what do they bind?
Family of 3 subunits which binds GDP/GTP
What do GDP/GTP bind to?
GDP/GTP bind to largest subunit which is the alpha subunit
What are G proteins held in the membrane by?
Held in the membrane by anchors by beta and gamma subunits
Based on structure, how many main families do G proteins have?
5 main famillies
What happens when GPCR activated?
When GCPR activated, G proteins split apart and alpha subunit interacts with enzymes
Steps of the activation of G protein receptors
When receptor activated, it causes and effect on alpha subunit
Conformational change
Alpha subunit now has higher affinity to GTP than GDP
Once GDP binds, alpha subunit dissociates
Alpha subunit breaks into alphaGs, alphaGi and alpha Gq/11
What does alpha Gs do?
Stimulates adenylate cyclase which makes cAMP from ATP
What does alpha Gi do?
Inhibits adenylate cyclase which means cAMP levels go down
What does alpha Gq/11 do?
Stimulates phospholipase c
In the alpha Gs pathway, what is the final effect?
Final effect is ion channels, enzymes and transport proteins
What is cAMP broken down by?
cAMP broken down by phosphodiesterase
What does activated alpha Gq have a specificity to?
Activated alpha Gq has specificity for enzyme phospholipase C
What does phospholipase C work on?
Works on PIP2
