Introduction to Signal-Transduction Pathways

A signal transduction pathway is a chain of events that converts messages into a physiological response.

extracellular

The conversion of information, signaling molecules into a downstream message is known as transduction.

molecular physiological

In a signal-transduction pathway, the can be a hormone or neurotransmitter.

SIGNAL

The receptor or ion channel in a signal-transduction pathway is referred to as the .

TRANSDUCER

A second messenger is typically the in a signal-transduction pathway.

EFFECTOR

In signal transduction, the release of the primary is the first key step.

messenger

A molecule that stimulates downstream signaling upon binding is called an .

agonist

A molecule that inhibits downstream signaling upon binding is known as an .

antagonist

Common second messengers include cyclic AMP (cAMP), cyclic GMP (cGMP), and ions.

Calcium

The process of using common second messengers in multiple pathways creates among cellular signals.

cross-talk

Epinephrine signaling is associated with responses and muscle contraction.

fight-or-flight

The insulin signaling pathway primarily facilitates uptake in cells.

glucose

The epidermal growth factor receptor stimulates gene expression when activated.

growth-promoting

A large class of cell-surface receptors that transmit diverse signals are known as receptors.

Seven-Transmembrane-Helix (7TM)

Ligand binding to a 7TM receptor induces a conformational change that activates a protein.

G

The α subunit of a heterotrimeric G protein exchanges GDP for when activated.

GTP

G proteins promote hydrolysis of bound GTP to GDP via their intrinsic activity.

GTPase

The hormone bound activated receptor can reset through hormone from the receptor.

dissociation

Phosphoinositide cascade is activated by some 7TM receptors, like receptors.

α-adrenergic

Diacylglycerol (DAG) activates __ during signaling.

protein kinase C (PKC)

Calmodulin undergoes conformational changes upon binding ions.

Ca$^{2+}$

Insulin facilitates glucose uptake by promoting translocation of glucose to cell surfaces.

transporters

Insulin binds to its receptor, which exists as a __ with α and β chains.

homodimer

PI3K converts PIP2 into , aiding recruitment of signal molecules.

PIP3

The binding of insulin promotes increased glucose transporter on cell surfaces.

presence

Insulin signaling is terminated internally by phosphatases that remove from active sites.

phosphorylation

EGF stimulates cell growth by binding to its and causing receptor dimerization.

receptor

Activation of Ras initiates a signaling cascade involving phosphorylation of factors and kinases.

transcription

Termination of EGF signaling occurs through phosphatases that remove phosphoryl groups and the action of -activating proteins.

GTPase

Mutations in genes encoding signal transduction proteins can lead to various .

cancers

The human olfactory system has about different receptors for specific odorants.

400

Rhodopsin is responsible for vision by absorbing light and initiating a signaling cascade through activation.

transducin

The net effects of intracellular signaling cascades include changes to processes.

physiological

Heterotrimeric G proteins consist of α, β, and subunits.

γ

The process by which receptors are phosphorylated and prevent signaling is called .

desensitization

Common second messengers can diffuse freely and influence processes throughout the .

cell

One of the common second messengers that initiates the release of Ca$^{2+}$ from the endoplasmic reticulum is .

IP3

EGF's action on cellular processes is mediated through activation.

Ras

Insulin receptors function as that contribute to glucose metabolism regulation.

tyrosine kinases

Calcium ions activate various proteins, including __, which modulate cellular responses.

kinases

A characteristic of signal transduction pathways is their ability to maintain through feedback regulation.

homeostasis

Insulin receptor auto-phosphorylation is one mechanism that regulates the process.

signaling

The intrinsic GTPase activity of G proteins provides a means for signaling.

terminating

In signal transduction, the binding of a signal molecule to a receptor is equivalent to a 'lock-and-key' model and demonstrates to a receptor.

complementarity

Second messengers often create a cascade effect, significantly the original signal.

amplifying

Epinephrine's physiological responses include increasing heart rate and metabolic rate.

enhancing

In signal transduction, phosphoinositide metabolism plays a crucial role in signals initiated by receptors.

7TM

Calmodulin's structure allows it to undergo conformational changes that are critical for signaling.

calcium-mediated

After binding, the G protein subunit Gα becomes active when it attaches to .

GTP

Calcium ions can leave the endoplasmic reticulum and participate in various cellular .

processes

The hormone-induced activation of receptors often results in the employment of kinases.

serine/threonine

Termination of insulin signaling can also be achieved through phosphate activity.

protein

The signaling cascades activated by EGF can lead to changes in activity within the nucleus.

gene expression

In the presence of calcium, calmodulin can activate other or signaling molecules.

proteins

The α subunit of G proteins is inactive when bound to .

GDP

Epidermal Growth Factor stimulates pathways crucial for __ and healing.

cell growth

Insulin signaling pathways are vital for maintaining levels in the blood.

glucose

The conversion of PIP2 into additional second messengers is mediated by .

phospholipase C

Detrimental mutations in signal transduction proteins often lead to uncontrolled proliferation.

cell