Chapter15Pt1

Cell Signaling

The process through which cells communicate with each other using extracellular messenger molecules.

Autocrine signaling

A type of cell signaling where the cell secretes a hormone or chemical messenger that binds to receptors on its own surface.

Paracrine signaling

A form of cell signaling where the signaling molecule affects neighboring cells by diffusing through the extracellular space.

Endocrine signaling

A form of cell signaling where hormones are released into the bloodstream to act on distant target cells.

Ligand

A molecule that binds to a receptor to elicit a response.

Signal transduction

The process by which a chemical or physical signal is transmitted through a cell as a series of molecular events.

G-protein coupled receptors (GPCRs)

A large family of membrane receptors that respond to various external signals and activate intracellular signaling pathways.

Second messenger

Molecules such as cAMP or calcium ions that relay signals received by cell surface receptors to target molecules inside the cell.

cAMP (cyclic adenosine monophosphate)

A second messenger that is produced from ATP and involved in transmitting signals from a variety of hormones and other signaling molecules.

Phospholipase C

An enzyme that cleaves phosphatidylinositol 4,5-bisphosphate to generate inositol trisphosphate (IP3) and diacylglycerol (DAG), which act as second messengers.

Protein kinase C (PKC)

An enzyme activated by diacylglycerol (DAG) that phosphorylates serine and threonine residues on target proteins.

Inositol 1,4,5-trisphosphate (IP3)

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

G protein

A molecular switch that transmits signals from GPCRs to effector proteins, existing in various configurations like Gs, Gi, and Gq.

Signal amplification

The process where a single signaling event leads to a large effect in the cell, often through the action of second messengers.

cAMP-dependent protein kinase (PKA)

An enzyme that is activated by cAMP and phosphorylates various target proteins to propagate the cellular response.

Glycogen breakdown

The process of breaking down glycogen into glucose, stimulated by hormones such as glucagon and epinephrine.

CREB (cAMP response element-binding protein)

A transcription factor activated by PKA that regulates gene expression in response to cAMP signals.

AKAPs (A-kinase anchoring proteins)

Proteins that anchor PKA to specific subcellular locations to facilitate signal transduction.

Rhodopsin

A photosensitive GPCR found in photoreceptor cells of the retina, essential for vision.

Protein-tyrosine kinases (PTKs)

Enzymes that phosphorylate tyrosine residues on target proteins; divided into receptor and non-receptor types.