Signal Transduction Pathways

This set of flashcards covers the key concepts related to signal transduction pathways, mechanisms of receptor activation, types of messengers, and major biochemical processes involved.

Signal Transduction

The diverse sequences of events that link receptor activation to cellular responses.

Receptor Activation

The change in the confirmation of the receptor caused by the binding of a messenger.

Water-Soluble Messengers

Chemical messengers that cannot readily enter cells and bind to receptors on the plasma membrane.

First Messenger

The extracellular chemical messenger that binds to specific plasma membrane receptors.

Second Messenger

Substances that enter or are generated in the cytoplasm as a result of receptor activation.

Protein Kinase

An enzyme that phosphorylates other proteins by transferring a phosphate group from ATP.

Phosphorylation

The process of adding a phosphate group to a protein, altering its activity.

Ligand-Gated Ion Channels

Receptors that are also ion channels, which change shape upon binding a ligand, allowing ions to flow through.

G Protein

A molecular switch that transmits signals from a receptor to other proteins, often affecting ion channels.

Affinity

The strength with which a chemical messenger binds to its receptor.

Saturation

The degree to which receptors are occupied by messengers.

Antagonist

A molecule that competes with a ligand for binding to its receptor but does not activate signaling.

Agonist

A chemical messenger that binds to a receptor and triggers the cell's response.

Down-Regulation

A decrease in the total number of target cell receptors due to high extracellular concentration of the messenger.

Up-Regulation

An increase in the total number of target cell receptors due to low extracellular concentration of the messenger.

Cyclic AMP (cAMP)

A second messenger generated from ATP, activating protein kinases within cells.

Diacylglycerol (DAG)

A second messenger that activates protein kinase C and is produced from the breakdown of phosphatidylinositol bisphosphate.

Inositol Triphosphate (IP3)

A second messenger that causes the release of calcium ions from the endoplasmic reticulum.

Eicosanoids

Biologically active lipids derived from arachidonic acid that have various effects on cell activity.