G Protein-Coupled Receptors I

These flashcards cover important terminology and concepts related to G Protein-Coupled Receptors, their signaling mechanisms, and associated physiological processes.

G Protein-Coupled Receptor (GPCR)

A type of receptor that spans the cell membrane and is involved in transmitting signals from extracellular molecules to intracellular responses.

Heterotrimeric G Proteins

Proteins composed of three subunits (α, β, γ) that transmit signals from GPCRs to effector proteins.

Effector Proteins

Proteins that are activated by G proteins and carry out the cellular response, such as adenylyl cyclase and phospholipase C.

Second Messenger

Intracellular signaling molecules that mediate the effects of GPCR activation, such as cAMP and IP3.

cAMP (cyclic adenosine monophosphate)

A second messenger produced from ATP by the action of adenylyl cyclase, involved in various signaling pathways.

PKA (Protein Kinase A)

An enzyme activated by cAMP that phosphorylates target proteins to elicit a cellular response.

ADENYLYL CYCLASE

An effector protein that converts ATP to cAMP; activated by the Gsα subunit.

Giα Subunit

A G protein subunit that inhibits adenylyl cyclase, leading to decreased levels of cAMP.

GRK (G Protein-Coupled Receptor Kinase)

An enzyme that phosphorylates activated GPCRs, leading to their desensitization.

Arrestin

A protein that binds to phosphorylated GPCRs and facilitates their endocytosis or degradation.

Phospholipase C

An effector protein that hydrolyzes phosphatidylinositol 4,5-bisphosphate to produce IP3 and DAG.

Ligand

A signaling molecule that binds to a receptor to trigger a cellular response, such as adrenaline or acetylcholine.

Fight-or-Flight Response

A physiological reaction that occurs in response to perceived harmful events, attacks, or threats to survival.

Desensitization

The process by which a receptor becomes less responsive to stimulation due to prolonged or repeated activation.

Cardiac Muscle Contraction vs. Relaxation

Contraction is mediated by adrenaline via β₁-adrenergic receptors (Gsα), while relaxation is mediated by acetylcholine via M2 muscarinic receptors (Giα).

CREB (cAMP Response Element-Binding Protein)

A transcription factor activated by PKA that regulates gene expression related to glucose metabolism.