Video: 15.1 G Protein Signaling Flashcards
When G-protein is inactive this means….
There is no signal from the G-protein receptor and GDP is a G-protein subunit bound
When G-protein is active this means…
There is a signal from the active G-protein receptor and GTP is bound to G-protein subinit
GTP binding to G-protein subunits means….
GTP binding activates G-protein subunits, subunits either stay together or dissociate into alpha subunit and beta complex
Active GTP bound alpha subunit means…
Alpha subunit will bind to the target protein and regulate the target protein
Active alpha subunit bound to target protein means…
the target protein with send a downstream of target signaling cascade
When does the alpha subunit rebind with B- complex?
when alpha subunit hydrolyzes GTP to GDP inactivation the subunit
What protein speeds up the hydrolysis of alpha subunit?
RGS
Which side of the plasma membrane has abundant GTP?
Cytosolic side
Prolong stimulation of G- protein receptor causes….
inactivation of receptor by GRK (Receptor Kinase)
What does GRK (Receptor Kinase) do?
phosphorylates ATP to ADP inactivating G-protein receptor
promoting arrestin binding to agonist-activated GPCRs and function to turn off receptor interaction with heterotrimeric G proteins,
What happens when G-protein coupled receptor is phosphorylated?
binds to arrestin with high affinity and inactivates receptor preventing an interaction with G-protein
What inactivates G-protein coupled receptor?
Binding with arrestin
What inactivates G-protein subunits?
Lack of stimulus from G-protein coupled receptor
Hydrolysis of GTP to GDP
What activates G-protein subunits?
Stimulus from G-protein coupled receptors
Binding GTP to subunits
