Signal Transduction and Cell Cycle Lecture Notes

Vocabulary-style flashcards covering the key concepts of Signal Transduction (Chapter 16) and the Cell Cycle (Chapter 18), including signaling types, molecular switches, receptor pathways, and experimental techniques.

Signal Transduction

The multi-step process where a cell receives a signal, amplifies it via second messengers, activates effector proteins, and produces a cellular response.

Juxtacrine Signaling

A form of cell signaling that occurs through direct contact between cells.

Synaptic Signaling

A type of signaling that involves communication from a neuron to a target cell.

Paracrine Signaling

Local signaling where a cell targets nearby cells.

Autocrine Signaling

A self-signaling mechanism where a cell produces a signal that it also responds to.

Hormonal Signaling

Long-distance signaling mediated through the blood.

Kinase

A molecular switch that adds a phosphate group to a protein (phosphorylation) to turn it "ON," changing its shape and affecting function.

Phosphatase

An enzyme that removes a phosphate group from a protein to turn it "OFF."

G Proteins

Molecular switches that are "OFF" when bound to GDP and "ON" when bound to GTP.

GEF (Guanine Nucleotide Exchange Factor)

The factor that activates G proteins by facilitating the exchange of GDP for GTP.

GAP (GTPase-Activating Protein)

The factor that inactivates G proteins by promoting the conversion of GTP to GDP.

Fast Signaling

A signaling response that modifies existing proteins.

Slow Signaling

A signaling response that requires gene expression.

Ion Channel-Coupled Receptors

Ligand-gated ion channels that open to allow the flow of ions when a ligand binds.

GPCRs (G Protein-Coupled Receptors)

Receptors that, upon ligand binding, cause a G protein to split into an $\alpha$-subunit and a $\beta/\gamma$ complex to activate effectors.

cAMP Pathway

A pathway where the stimulatory $\alpha$-subunit activates adenylyl cyclase (AC) to convert ATP into cAMP, which then activates PKA.

PLC Pathway

A pathway where the $\beta/\gamma$ complex activates PLC (Phospholipase C).

RTKs (Enzyme-Coupled Receptors)

Receptor Tyrosine Kinases that dimerize and undergo tyrosine phosphorylation upon ligand binding to recruit adapter proteins.

PKA (Protein Kinase A)

A Ser/Thr kinase activated by cAMP that phosphorylates diverse substrates for signal amplification.

PKC (Protein Kinase C)

A protein kinase activated by a combination of DAG and $Ca^{2+}$.

CAMK

A protein kinase activated by $Ca^{2+}/calmodulin$.

MAPK

A protein kinase involved in gene expression, activated by the Ras cascade.

Akt Pathway

A major pathway where PI3K converts PIP2 to PIP3 to activate Akt, regulating cell growth, survival, and metabolism.

PTEN and SHIP

Phosphatases that act as inhibitors in the Akt signaling pathway.

Affinity Chromatography

An experimental technique where a ligand is attached to beads to pull out a specific receptor.

Immunoprecipitation

A technique using an antibody to pull down a protein and its associated binding partners.

Constitutively Active

A reverse genetics state where a pathway is signaling permanently.

Dominant Negative

A reverse genetics state where a pathway is blocked.

Cell Cycle Phases

The stages of the cell cycle: G1 (growth), S (DNA synthesis), G2 (growth), and M (cell division).

CDKs (Cyclin-Dependent Kinases)

Kinases that are always present in the cell cycle but remain inactive unless bound to cyclins; regulated by inhibitors like p21 or p27.

Cyclins

Proteins that fluctuate during the cell cycle; their levels increase via transcription and decrease via ubiquitination.