Flashcards in 7. Effector Mechanisms Deck (23)
Define the term agonist
Chemical that binds to a receptor and activates it
Define the term antagonist
Bonds to a receptor and blocks it
Describe the structure of a GPCR receptor
Single polypeptide chain
7 transmembrane domains
Extracellular N terminal
Intracellular C terminal
What regions can act as a binding site on GPCRs?
2-3 transmembrane domains
N terminal region
Describe the mechanism of how a GPCR works
Ligand binds - causes conformational change
Activated GPCR interacts with G protein
This causes GDP for GTP exchange of the alpha subunit
The alpha beta gamma subunits dissociate into alpha GTP and beta gamma subunits
Each can interact with effector proteins
Interaction lasts until the alpha subunit GTPase hydrolysis GTP into GDP and the subunits reform the complex
What is the Gs effector?
Stimulating adenyl cyclase
What is the Gi effector?
Inhibiting adenyl cyclase
What is the Gq effector?
Stimulates phospholipase c
What is the Gt effector?
Stimulates Cyclic GMP phosphodiesterase
What G protein do Beta adrenoreceptors couple with?
What G protein do alpha 1 adrenoreceptors couple with?
What G protein do alpha 2 adrenoreceptors couple with?
What G protein does rhodopsin couple with?
What G protein does M2/M4 receptors couple with?
What G proteins do M1/M3 couple with?
What is the "ligand" for rhodopsin?
What toxin produces cholera?
Cholera toxin, CTx
What toxin produces whooping cough?
Pertussis toxin, PTx
How does cholera toxin affect G proteins?
Eliminates GTPase activity of Gs therefore Gs becomes irreversibly activated
How does Pertussis toxin affect proteins?
It interferes with GDP/GTP exchange on Gi therefore Gi becomes irreversibly inactivated
What does adenyl cyclase interact with?
Protein kinase A, activates the catalytic subunits allowing them to phosphorylated other proteins
What does phospholipase C interact with?