BIOL 651 Quiz 6: Signaling Mechanisms and Pathways

Intracellular signals

Signals that occur within a cell, typically involving signaling molecules or pathways that lead to changes in the cell's behavior or function.

Intercellular signals

Signals that occur between cells, where one cell sends a signal to another, often mediated by extracellular signaling molecules.

Ionotropic receptors

Ligand-gated ion channels that open when bound by a ligand, allowing ions like Na+, K+, or Ca++ to pass through and produce an immediate change in membrane potential.

Metabotropic receptors

G-protein-coupled receptors that trigger a cascade of intracellular signaling events, often involving second messengers, leading to a cellular response.

Second messenger

A small intracellular signaling molecule produced or released in response to the activation of a receptor by a primary messenger, helping amplify and propagate the signal within the cell.

Signal amplification

A common theme in second-messenger signaling pathways where a single activated receptor can stimulate the production of many second messenger molecules.

Gq protein

A G-protein that produces two second messengers: IP3 (inositol trisphosphate) and DAG (diacylglycerol).

IP3

Inositol trisphosphate, a second messenger that stimulates the release of calcium from the endoplasmic reticulum.

DAG

Diacylglycerol, a second messenger that activates protein kinase C (PKC).

Calcium signaling

A versatile signaling mechanism used in various cellular processes such as muscle contraction, neurotransmitter release, and gene expression.

Concentration control

The process by which cells maintain low intracellular calcium levels and rapidly increase them in response to signals.

CREB

cAMP response element-binding protein, a transcription factor that promotes the transcription of target genes when phosphorylated.

Phosphokinase C (PKC)

An enzyme that is initially activated by diacylglycerol (DAG) and requires calcium for full activation.

Paracrine signaling

A type of signaling that involves the release of signaling molecules from one cell that affect nearby cells.

Cyclic AMP (cAMP)

A common second messenger involved in various signaling pathways.

Calmodulin

A protein that can be activated by calcium and plays a role in various cellular processes.

Protein kinase C (PKC)

An enzyme that is activated by diacylglycerol and calcium, involved in various signaling pathways.

Neurotransmitter

A signaling molecule that transmits signals across a chemical synapse from one neuron to another.

Hormone

A signaling molecule that is released into the bloodstream and affects distant target cells.

Cytokine

A signaling molecule that is involved in cell signaling, particularly in immune responses.

Phosphorylation cascades

A series of protein modifications that can amplify signals and lead to various cellular responses.

Dendritic spines

Small protrusions on neurons known for their complex internal structure, including highly organized cytoskeletal elements and various molecular machinery involved in synaptic signaling and plasticity.

Gq proteins

Proteins that typically activate phospholipase C (PLC), leading to the production of DAG and IP3, which release calcium from the endoplasmic reticulum and activate PKC.

Adenylyl cyclase

An enzyme associated with Gs proteins, not Gq.

Phospholipase C (PLC)

An enzyme directly activated by Gq that produces DAG and IP3.

Diacylglycerol (DAG)

A second messenger involved in PKC activation.

cGMP

A second messenger involved in various signaling pathways, activated by phosphokinase G (PKG) and cyclic nucleotide-gated membrane channels.

Amplification in signaling

Occurs at steps involving second messenger production and subsequent activation of downstream targets like protein kinases.

CREB signaling

Involves activation via a cAMP-dependent pathway, mediated by Gs proteins.

Calcium channels in the endoplasmic reticulum

Opened by IP3, produced by PLC, as part of Gq signaling.

Calcium-binding proteins

Activated due to the increase in intracellular calcium, a downstream effect of Gq signaling.

Phosphokinase G (PKG)

Activated by cGMP.

Cyclic nucleotide-gated membrane channels

Regulated by cyclic nucleotides like cGMP.

Calcium ions

Act as second messengers in many cellular processes.

Signaling via Gq

Involves activation of PLC, which acts on membrane phospholipids.

Signaling via phospholipase C

Involves breakdown of membrane phospholipids into DAG and IP3.

Signaling via diacylglycerol

Involves DAG as a product of membrane phospholipid breakdown.

Signaling via endocannabinoids

Involves signaling pathways mediated by compounds derived from membrane phospholipids.

G-protein coupled receptors (GPCR)

Receptors that can activate Gs proteins, leading to cAMP production.