G-protein coupled receptor pathways and second messenger systems tested on USMLE Step 1.
34 cards · basic cards · AI-written, checked twice. Edit anything.
- How many transmembrane domains does a GPCR have?
- Seven
- What are the three subunits of a heterotrimeric G protein?
- Alpha, beta, and gamma
- In the resting (inactive) state, what nucleotide is bound to the G-alpha subunit?
- GDP
- Ligand binding to a GPCR causes the alpha subunit to exchange ____ for GTP.
- GDP
- What intrinsic enzymatic activity terminates G-alpha subunit signaling?
- GTPase activity, which hydrolyzes GTP back to GDP
- Which G-alpha subunit stimulates adenylyl cyclase?
- Gs alpha
- Which G-alpha subunit inhibits adenylyl cyclase?
- Gi alpha
- Which G-alpha subunit activates phospholipase C?
- Gq alpha
- Adenylyl cyclase converts ATP into the second messenger ____.
- cAMP
- What enzyme does cAMP activate?
- Protein kinase A (PKA)
- What happens to PKA's catalytic subunits when cAMP binds its regulatory subunits?
- They are released from the holoenzyme and become active
- What enzyme degrades cAMP to AMP?
- Phosphodiesterase
- What two second messengers does phospholipase C produce from PIP2?
- IP3 and DAG
- What does IP3 trigger in the cell?
- Release of calcium from the endoplasmic reticulum
- What enzyme does DAG activate?
- Protein kinase C (PKC)