GPCRs Flashcards
1
Q
describe the general scheme of GPCR signaling
A
- ligand binds to extracellular domain of receptor, inducing a conformational change in receptor
- when inactive Gprotein associates with ligand-bound receptor, the receptor helps the alpha subunit turn GDP into GTP, activating the G protein
- alpha subunit separates from beta-gamma dimer.
- alpha is active unitl its innate GTPase activity hydrolyzes GTP
- beta-gamma dimer is active as long as it is separated from alpha - actvated G protein components affect downstream targets
- ex: some activated alpha subunits can activate adenylyl cyclase to convert ATP to cAMP
2
Q
What are the functions of GEF’s (guanine nucleotide exchange factors), GAP’s (GTPase Activator Proteins), and RGS’s (Regulators of G Protein Signaling)?
A
- regulate GTPase activity of alpha subunit of G protein
- control how long the G proteins are activated for
3
Q
are all G-protein subunits the same?
A
- no, there are multiple family members of each G protein subunit
- some will activate signaling pathways, others will inhibit signaling pathways
3
Q
what are 3 examples of second messengers?
A
- cAMP
- calcium ions
- PIP2
4
Q
what type of molecules is PIP2 and what signaling molecules can be made from it? what type of enzyme is involved in that process?
A
- it is a type of membrane phospholipid
- IP3 is the signaling molecule that can be made from it
- DAG (diacylglyceride) is also madae
- Phospholipase C (PLC) cleave PIP2 into IP3 (enzyme activated by G-protein)