BIOL408 Unit 3- GPCRs (cAMP + Gq)

ion channel

pore forming transmembrane channels that allow ions to pass through

what are the three kinds of ion channels?

ligand gated, mechano-sensitive, and voltage-gated

what is the structure of GPCRs?

contains 7 transmembrane helices and interactions occur within the cytoplasmic loops

G-protein

signaling molecules that are controlled by the binding of GTP/GDP

types of G-proteins

Gi, Gs, Gq, G12/23

how are G-proteins activated?

signal molecule bind to GPCR, which allows it to bind to the G-protein, the G-protein then exchanges GDP for GTP, then the G-protein dissociates from the receptor and splits into the a and b/Y subunits

cAMP

intracellular messenger that is regulated by GPCRs

how do G-proteins interact with cAMP?

cAMP is increased by Gs and decreased by Gi

what molecules are involved in the cAMP pathway?

adenylyl cyclase, ATP, cAMP, PKA, and CREB

what are the steps of the cAMP pathway (6)?

GPCR ligand binding activates the G-protein, G-protein activates adenylyl cyclase, converting ATP to cAMP, cAMP activates PKA by binding to its inhibitor, PKA moves to nucleus and phosphorylates CREB, CRED activates transcription of target gene

Gq protein

activate phospholipid based second messengers

what molecules are involved in the Gq pathway?

Gq alpha unit, PLCB, PIP2, DAG, IP3

what is the Gq pathway?

ligand binds to G-protein, Gq alpha unit activated, Gq activates PLC, PLC cleaves PIP2 into DAG and IP3

DAG

activates protein kinase C (PKC)

IP3

ligand for Ca2+ channels