Molecular Cell Biology - G Protein-Coupled Receptors III

Flashcards covering key terms and concepts related to G protein-coupled receptors, nitric oxide production, signaling pathways, and related clinical relevance.

Nitric Oxide

An inorganic gas synthesized by the enzyme Nitric Oxide Synthase (NOS), involved in various signaling pathways.

Nitric Oxide Synthase (NOS)

An enzyme responsible for the production of nitric oxide (NO) from L-arginine.

eNOS

Endothelial Nitric Oxide Synthase, which produces NO in endothelial cells and is calcium-dependent.

nNOS

Neuronal Nitric Oxide Synthase, which also produces NO in neuron cells and is calcium-dependent.

iNOS

Inducible Nitric Oxide Synthase, which produces NO in response to stress and is calcium-independent.

G Protein-Coupled Receptors (GPCRs)

A large family of cell surface receptors that respond to various ligands and activate intracellular signaling pathways.

M3 Muscarinic Receptors

A type of GPCR that binds acetylcholine and plays a crucial role in eNOS activation.

Acetylcholine (ACh)

A neurotransmitter that induces eNOS activation in endothelial cells, leading to vasodilation.

Calcium-Calmodulin Complex

A signaling complex formed by calcium binding to calmodulin, activating eNOS.

Soluble Guanylate Cyclase

An enzyme activated by NO that converts GTP to cGMP, leading to smooth muscle relaxation.

PKG (cGMP-specific protein kinase G)

An enzyme activated by cGMP that mediates smooth muscle relaxation and vasodilation.

Myosin Light Chain Phosphatase (MLCP)

An enzyme that dephosphorylates myosin light chains in smooth muscle, promoting relaxation.

Erectile Dysfunction (ED)

The inability to achieve or maintain an erection, often related to impaired NO signaling.

Sildenafil (Viagra)

A PDE-5 inhibitor used to treat ED by increasing cGMP levels and enhancing erectile response.

Acetylcholinesterase (AchE)

An enzyme that breaks down acetylcholine in the synaptic cleft, terminating the muscle contraction signal.

Flaccid Paralysis

Inability of muscles to contract due to insufficient acetylcholine activity at the neuromuscular junction.

Spastic Paralysis

Continuous muscle contraction due to excessive acetylcholine activity, often as a result of AchE inhibition.

Oxidative Stress

An imbalance between free radicals and antioxidants in the body, often leading to eNOS uncoupling.

Angina Pectoris

A condition characterized by chest pain due to reduced blood flow to the heart muscle.

Nitroglycerin

A medication used to treat angina pectoris by releasing NO and promoting vasodilation.

Endothelial Dysfunction

A pathological condition affecting the inner lining of blood vessels and associated with cardiovascular diseases.