Signaling 2

Ligand

A molecule that binds to a receptor to initiate a signaling process.

Receptor

A protein on cell surfaces or within cells that binds to ligands.

Signal Transduction

The process of converting an extracellular signal into an intracellular message.

Secondary Messengers

Molecules like cAMP or Ca²⁺ that are involved in signal transduction.

Signal Amplification

A process where one ligand-receptor interaction activates multiple downstream molecules.

Adenylate Cyclase

An enzyme activated by GPCRs that converts ATP to cAMP.

Effectors

Proteins or enzymes that bring about a cellular response.

Ion Channels

Proteins that facilitate the movement of ions across cellular membranes.

Transcription Factors

Proteins that regulate gene expression by binding to DNA.

Dephosphorylation

The removal of phosphate groups from proteins, often inactivating them.

Endocytosis

The process by which cells internalize substances from their surface.

G proteins

Heterotrimeric proteins involved in transmitting signals from receptors to effector proteins.

GPCR Desensitization

A mechanism that reduces receptor responsiveness after prolonged exposure to a ligand.

Endocrine Signaling

Hormonal signaling across long distances in the body.

Paracrine Signaling

Signaling that affects nearby cells.

Neuronal Signaling

Rapid signals sent via axons and synapses.

Contact-Dependent Signaling

Direct signaling that requires physical contact between cells.

Steroid Hormones

Hormones that can diffuse across cell membranes and bind to intracellular receptors.

Transcription Factors

Complexes that regulate gene expression in response to steroid hormones.

TOR Kinase

A kinase that controls cell growth and metabolism.

MAPK Kinase

Kinases involved in cell proliferation, differentiation, and stress responses.

Integrins

Proteins that mediate cell adhesion to the extracellular matrix.

Focal Adhesion Complexes

Structures that link the cytoskeleton to the extracellular matrix.

GTP

A molecule that activates G proteins when bound.

GDP

A molecule that inactivates G proteins when bound.

GPCRs

G protein-coupled receptors involved in transmitting various signals.

cAMP Pathway

A signaling pathway where cAMP activates protein kinase A (PKA).

Phosphodiesterase

An enzyme that degrades cAMP to AMP, terminating the cAMP signal.

IP3 Pathway

A pathway activated by GPCRs that releases Ca²⁺ from the endoplasmic reticulum.

DAG

A secondary messenger that activates protein kinase C (PKC).

RTK Signaling

Signaling pathways initiated by receptor tyrosine kinases.

Ras

A GTPase that is activated in RTK signaling pathways.

MAPK Cascade

A series of protein kinase activations triggered by Ras leading to transcriptional changes.

GEFs

Guanine Exchange Factors that activate GTPases.

GAPs

GTPase-Activating Proteins that inactivate GTPases.

Calmodulin

A protein that mediates calcium signaling upon activation by Ca²⁺.

Notch-Delta Signaling

A contact-dependent signaling pathway that regulates cell differentiation.

Kinase Cascades

Series of kinases activated in sequence, leading to a significant cellular response.

Phosphoproteins

Proteins modified by the addition or removal of phosphate groups.