GPCR and RTK Signaling Flashcards

Vocabulary flashcards covering GPCR signaling, RTK activation, second messengers, and molecular switch mechanisms based on the lecture notes.

G-Protein-Coupled Receptors (GPCRs)

Cell-surface receptors often associated with the nervous system, senses, behavior, and sleep that relay signals via heterotrimeric G-proteins.

Enzyme-Coupled Receptors

Receptors such as EGF, TGF, and Insulin associated with roles in development, cancer, and tissue renewal.

Ion-Channel-Coupled Receptors

Receptors that control the movement of molecules across membranes, affecting membrane potential and ion concentrations.

GEF (Guanine nucleotide exchange factor)

A protein that activates an inactive GTPase by stimulating the release of GDP so it can bind GTP.

RGS (Regulators of G-protein Signaling)

Proteins that accelerate the hydrolysis of GTP to GDP to inactivate G-protein $\alpha$-subunits.

GRK (GPCR kinase)

A kinase that phosphorylates only activated GPCRs to initiate the inactivation process.

Arrestin

A protein that binds to phosphorylated GPCRs, leading to receptor desensitization and inactivation by preventing G-protein binding.

Adenylyl Cyclase (AC)

An enzyme in the plasma membrane that transforms ATP into the second messenger cAMP using the energy of two phosphates.

Cyclic AMP (cAMP)

A small signaling molecule that freely diffuses in the cytoplasm and activates Protein Kinase A (PKA).

PKA (Protein Kinase A)

A kinase activated by cAMP that traffics to the nucleus to activate CREB.

CREB (cAMP-response element binding protein)

A transcription regulator activated via phosphorylation by PKA to initiate target gene expression.

Phospholipase C (PLC)

An enzyme that splits $PI(4,5)P_2$ into the second messengers diacylglycerol (DAG) and inositol trisphosphate ($IP_3$).

$IP_3$ (Inositol trisphosphate)

A small molecule that opens $Ca^{2+}$ channels on the endoplasmic reticulum (ER).

$DAG$ (Diacylglycerol)

A lipid-derived second messenger that, along with $Ca^{2+}$, activates Protein Kinase C (PKC).

Notch Signaling

A contact-dependent signaling pathway where specific proteins undergo proteolytic cleavage to release active fragments that translocate to the nucleus.

Hedgehog Signaling

A signaling cascade that regulates development by turning a transcriptional repressor into an activator.

Heterotrimeric GTP-binding proteins

Large G-proteins that relay signals directly from GPCRs.

Monomeric GTP-binding proteins

Small proteins that relay signals from many classes of cell surface receptors, including RTKs.

GAP (GTPase-activating proteins)

Proteins that inactivate GTPases by stimulating them to hydrolyze their bound GTP to GDP.

Protein Kinase

An enzyme that transfers a phosphate group from ATP to a protein to change its conformation and activity.

Protein Phosphatase

An enzyme that removes a phosphate group from a protein.

Receptor Tyrosine Kinase (RTK)

Transmembrane receptors with an intracellular kinase domain that phosphorylates Tyrosine (Y) residues on the receptor itself.

Trans-autophosphorylation

The process where dimerized RTKs phosphorylate each other's kinase domains upon ligand binding.

Sos (Son-of-Sevenless)

A Guanidyl Exchange Factor (GEF) involved in the RTK signaling pathway that activates Ras.

Size Exclusion Chromatography (SEC)

A method used to separate molecules based on size by filtration through a gel consisting of spherical beads with specific pore sizes.

Multiangle Light Scattering (MALS)

A technique used to measure the absolute molecular weight and size of macromolecules in solution based on the intensity of scattered light.