Notes in Cell Signaling (Morgan)

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Published	08/06/2024	{c1::Cells}} have to receive and respond to {{c2::signals from their environment}}.
Removal Requested	08/06/2024	{{c1::Cells}} have to work together in {{c2::tissues and organs}}.
Published	08/06/2024	A {{c1::signal}} secreted from one cell binds to a {{c2::receptor}} on another cell.
Published	08/06/2024	Binding of a signal to its receptor initiates a wide range of {{c1::intracellular changes}}.
Published	08/06/2024	{{c1::Cancer cells}} often have dysregulated {{c2::signaling pathways}}.
Published	08/06/2024	Modes of cell-cell signaling include {{c1::direct}}, {{c2::endocrine}}, {{c1::paracrine}}, and {{c2::autocrine}}.
Published	08/06/2024	A {{c1::ligand}} is a {{c2::signaling molecule}}.
Published	08/06/2024	A {{c1::receptor}} binds to a {{c2::ligand}}.
Published	08/06/2024	{{c1::Signal transduction}} involves a series of steps from the initial detection of a signal to the final {{c2::responses of the cell}}.
Published	08/06/2024	The first step in signal transduction is the binding of a {{c1::ligand (H)}} to a {{c2::receptor (R)}}.
Published	08/06/2024	A conformational change in the receptor ({{c1::R*}}) enables it to bind to and activate {{c2::signal transduction protein S1}}.
Published	08/07/2024	Activated {{c1::S1 (S1*)}} binds to and activates/inhibits {{c2::signal transduction protein S2}}.
Published	08/06/2024	{{c1::S2}} activates {{c2::S3, S4, S5}}.
Published	08/06/2024	Signal transduction proteins activate an {{c1::effector protein (E)}}, which can be an {{c2::enzyme, transcription factor, transport protein, or ion c…
Published	08/07/2024	Feedback control involves {{c1::S5}} inhibiting the receptor or an early protein in the {{c2::pathway}}.
Published	08/06/2024	Steroid hormones are derived from {{c1::cholesterol}}.
Published	08/06/2024	{{c1::Sex steroids}} are produced by the {{c2::gonads}}.
Published	08/06/2024	{{c1::Testosterone}}, {{c2::estrogen}}, and progesterone are types of sex steroids.
Published	08/06/2024	Corticosteroids are produced by the {{c1::adrenal gland}}.
Published	08/06/2024	Corticosteroids stimulate the production of {{c1::glucose}}.
Published	08/06/2024	Thyroid hormone is synthesized from {{c1::tyrosine}} in the {{c2::thyroid gland}}.
Published	08/06/2024	Thyroid hormone is important in {{c1::development}} and regulation of {{c2::metabolism}}.
Published	08/06/2024	Vitamin {{c1::D3}} regulates {{c2::Ca++ metabolism}} and bone growth.
Published	08/06/2024	Retinoids are synthesized from {{c1::vitamin A}}.
Published	08/06/2024	Retinoids are important in {{c1::development}}.
Published	08/06/2024	Steroid hormone ligands are {{c1::hydrophobic}}, allowing them to {{c2::diffuse across the plasma membrane}}.
Published	08/06/2024	Steroid hormone receptors are located in the {{c1::nucleus}} and act as {{c2::transcription factors}}.
Published	08/06/2024	Steroid hormone receptors can either {{c1::activate}} or {{c2::repress}} gene expression.
Published	08/06/2024	Steroid hormone receptors are part of the {{c1::nuclear receptor superfamily}} and contain domains for {{c2::ligand binding, DNA binding, and transcri…
Published	08/06/2024	Sex steroids pass through the {{c1::plasma membrane}} and bind to receptors in the {{c2::cytoplasm}}.
Published	08/06/2024	The ligand-receptor complex of sex steroids binds to DNA at the {{c1::hormone response element (HRE)}}.
Published	08/06/2024	The glucocorticoid receptor, in the absence of the hormone, is bound to {{c1::Hsp90 chaperone}}.
Published	08/06/2024	Glucocorticoid binding induces a conformational change in the receptor, displacing {{c1::Hsp90}} and forming a {{c2::dimer}}.
Published	08/06/2024	The glucocorticoid receptor dimer binds to regulatory DNA sequences and associates with {{c1::histone acetyltransferases (HAT)}}.
Published	08/06/2024	The thyroid hormone receptor binds to DNA in both the {{c1::presence}} and {{c2::absence}} of the hormone.
Published	08/06/2024	In the absence of thyroid hormone, the receptor acts as a {{c1::repressor}} by binding to corepressors with {{c2::histone deacetylase (HDAC)}} activit…
Published	08/06/2024	In the presence of thyroid hormone, the receptor undergoes a conformational change and acts as an {{c1::activator}}, binding to coactivators with {{c2…
Published	08/06/2024	Nitric oxide acts as a {{c1::paracrine}} signaling molecule over {{c2::short distances}}.
Published	08/06/2024	Nitric oxide signals in the {{c1::nervous}}, {{c2::immune}}, and circulatory systems.
Published	08/06/2024	Nitric oxide diffuses across the {{c1::plasma membrane}}.
Published	08/06/2024	Nitric oxide alters the activity of the {{c1::guanylyl cyclase}} enzyme, which synthesizes {{c2::cGMP}}.
Published	08/06/2024	Neurotransmitters such as {{c1::acetylcholine}} and {{c2::GABA}} are examples of small signaling molecules.
Published	08/06/2024	Neurotransmitters are {{c1::hydrophilic}} and bind to receptors on the {{c2::target cell surface}}.
Published	08/06/2024	G protein-coupled receptors (GPCRs) transmit signals to intracellular targets via {{c1::G proteins}}.
Published	08/06/2024	The structure of GPCRs is characterized by {{c1::seven membrane-spanning α helices}}.
Published	08/06/2024	Ligand binding to the extracellular domain of GPCR induces a {{c1::conformational change}}.
Published	08/06/2024	The activated G protein dissociates from the receptor and carries the signal to an {{c1::intracellular target}}.
Published	08/06/2024	The primary target enzyme of the G protein is {{c1::adenylyl cyclase}}, which converts {{c2::ATP to cAMP}}.
Published	08/06/2024	G protein structure is a {{c1::heterotrimer}} consisting of subunits {{c2::α, β, and γ}}.
Published	08/06/2024	In the resting state, the α subunit of the G protein is bound to {{c1::GDP}} and associated with {{c2::β and γ}} subunits.
Published	08/06/2024	In the active state, the cytosolic domain of the activated receptor acts as a {{c1::guanine exchange factor (GEF)}}.
Published	08/06/2024	The GTP-bound α subunit dissociates from the β and γ subunits and interacts with {{c1::intracellular targets}}.
Published	08/06/2024	The activity of the GTP-bound α subunit is terminated by hydrolysis of GTP to GDP by {{c1::GTPase activating proteins (GAPs)}}.
Published	08/07/2024	The G protein that stimulates adenylyl cyclase is called {{c1::Gs}}, while the one that inhibits it is called {{c2::Gi}}.
Published	08/07/2024	cAMP is synthesized from ATP by {{c1::adenylyl cyclase}} and degraded to AMP by {{c2::cAMP phosphodiesterase}}.
Published	08/06/2024	Most effects of cAMP are mediated by {{c1::protein kinase A (PKA)}}.
Published	08/06/2024	The βγ complex of G proteins can directly regulate proteins by binding to {{c1::ion channels}} and opening them.
Published	08/07/2024	Protein kinase A (PKA) is a tetramer composed of two {{c1::regulatory}} and two {{c2::catalytic}} subunits.
Published	08/07/2024	Activated PKA phosphorylates {{c1::serines}} on target proteins, amplifying the signal.
Published	08/07/2024	Active protein kinase A phosphorylates and activates {{c1::phosphorylase kinase}}, which in turn activates {{c2::glycogen phosphorylase}}.
Published	08/07/2024	Activated PKA enters the nucleus and phosphorylates the transcription factor {{c1::CREB}}.
Published	08/07/2024	Phosphorylation by protein kinase A is reversible, and the enzyme {{c1::protein phosphatase 1}} removes these phosphate groups.
Published	08/06/2024	Binding of a ligand to GPCR can lead to an increase in intracellular {{c1::Ca++}} via the {{c2::IP3-DAG}} pathway.
Published	08/06/2024	The α subunit of the G protein activates {{c1::phospholipase C}}, which cleaves PI(4,5)P2 to {{c2::IP3 and DAG}}.
Published	08/06/2024	IP3 binds to and opens {{c1::IP3-gated Ca++ channels}} in the endoplasmic reticulum, releasing Ca++ into the cytoplasm.
Published	08/06/2024	{{c1::DAG}} activates {{c2::protein kinase C (PKC)}}, which is recruited to the plasma membrane.
Published	08/06/2024	The largest family of enzyme-linked receptors are {{c1::tyrosine kinases}}, which phosphorylate substrates on {{c2::tyrosines}}.
Published	08/06/2024	Some receptors are not tyrosine kinases but stimulate {{c1::intracellular tyrosine kinases}}.
Published	08/06/2024	Receptor tyrosine kinases include {{c1::growth factor receptors}} such as EGF, PDGF, and {{c2::insulin}}.
Published	08/06/2024	The structure of receptor tyrosine kinases includes an {{c1::N-terminal ligand-binding domain}}, a single transmembrane α helix, and a cytosolic {{c2:…
Published	08/06/2024	The C-terminal segment of receptor tyrosine kinases contains {{c1::tyrosine residues}} that become phosphorylated by the receptor's own kinase.
Published	08/06/2024	Ligand binding to receptor tyrosine kinases induces {{c1::dimerization}} of the receptor.
Published	08/06/2024	Dimerization of receptor tyrosine kinases leads to {{c1::autophosphorylation}} of the receptor.
Published	08/06/2024	Autophosphorylation of receptor tyrosine kinases increases {{c1::protein kinase activity}} and creates {{c2::protein binding sites}} outside of the ca…
Published	08/06/2024	{c1::SH2 domains}} bind to peptides containing {{c2::phosphotyrosines}}.
Published	08/06/2024	EGF receptors are also known as {{c1::HER}} proteins in humans.
Published	08/06/2024	HER2 cannot bind {{c1::ligand}} but forms heterodimers with {{c2::HER1}}, {{c3::HER3}}, and {{c4::HER4}}.
Published	08/06/2024	Increased levels of {{c1::HER2}} protein can be associated with some {{c2::breast cancers}}.
Published	08/06/2024	HER2 gene amplification leads to {{c1::multiple copies}} of the HER2 gene and {{c2::increased}} HER2 protein levels.
Published	08/06/2024	HER2 signaling can be blocked with antibodies such as {{c1::Herceptin}}.
Published	08/06/2024	Nonreceptor tyrosine kinases are not tyrosine kinases themselves but stimulate intracellular {{c1::tyrosine kinases}}.
Published	08/06/2024	Cytokine receptors have a {{c1::N-terminal}} ligand-binding domain, a single {{c2::transmembrane}} α helix, and a cytosolic C-terminal domain.
Published	08/06/2024	Ligand binding to cytokine receptors causes {{c1::dimerization}} and {{c2::autophosphorylation}} of associated nonreceptor tyrosine kinases.
Published	08/06/2024	In the JAK-STAT pathway, JAK is a {{c1::nonreceptor}} tyrosine kinase that binds to the {{c2::C-terminus}} of the cytokine receptor.
Published	08/06/2024	STAT proteins are {{c1::transcription factors}} that are inactive in the cytoplasm until {{c2::phosphorylated}} by JAK.
Published	08/06/2024	STAT proteins bind via {{c1::SH2 domains}} to phosphotyrosine in the receptor's {{c2::cytoplasmic}} domain.
Published	08/06/2024	Once phosphorylated, STAT proteins {{c1::dimerize}} and translocate to the {{c2::nucleus}}.
Published	08/06/2024	The STAT dimer activates transcription of {{c1::target}} genes upon reaching the nucleus.
Published	08/06/2024	Src is important in signaling downstream of {{c1::cytokine receptors}}, {{c2::receptor tyrosine kinases}}, and receptors involved in cell-cell and cel…
Published	08/06/2024	Integrins are receptors for {{c1::extracellular matrix}} molecules and activate intracellular signaling pathways.
Published	08/06/2024	Integrins have no {{c1::enzymatic}} activity but activate the nonreceptor tyrosine kinase {{c2::FAK}}.
Published	08/06/2024	FAK {{c1::autophosphorylates}} on tyrosine and binds other signaling molecules, including {{c2::Src}}, via SH2 domains.
Published	08/06/2024	MAP kinases are part of a {{c1::cascade}} of protein kinases activated by growth factors and regulate cell growth and {{c2::differentiation}}.
Published	08/06/2024	Ras is a {{c1::guanine}} nucleotide-binding protein that is active when {{c2::GTP-bound}} and inactive when GDP-bound.
Published	08/06/2024	Guanine exchange factors (GEFs) {{c1::release}} GDP from Ras and replace it with {{c2::GTP}}, thereby activating Ras.
Published	08/06/2024	GTPase-activating proteins (GAPs) {{c1::hydrolyze}} GTP on Ras to GDP, which {{c2::inactivates}} Ras.
Published	08/06/2024	Ras is activated by receptor tyrosine kinases through a series of steps starting with {{c1::ligand}} binding and receptor {{c2::autophosphorylation}}.
Published	08/06/2024	After receptor autophosphorylation, Ras GEF binds via SH2 domains, stimulates exchange of {{c1::GDP}} for {{c2::GTP}} on Ras, and activates Ras.
Published	08/06/2024	Activated Ras-GTP stimulates {{c1::Raf}}, which then activates {{c2::MEK}} through phosphorylation.
Published	08/06/2024	MEK phosphorylates {{c1::ERK}}, which then phosphorylates target {{c2::proteins}} to regulate various cellular functions.
Published	08/06/2024	Mutated Ras is found in approximately {{c1::30%}} of human cancers and remains in the active {{c2::GTP-bound}} form.
Published	08/07/2024	Activated ERK induces transcription of {{c1::immediate}} early genes that control progression through the {{c2::cell cycle}}.
Published	08/06/2024	Elk-1 and {{c1::SRF}} (serum response factor) are examples of transcription factors induced by {{c2::ERK}}.
Published	08/07/2024	PI 3-kinase/Akt is a cell {{c1::survival}} pathway that generates second messengers from plasma membrane {{c2::phospholipids}}.
Published	08/07/2024	PI 3-kinase converts PIP to {{c1::PIP2}} and PIP2 to {{c2::PIP3}}.
Published	08/07/2024	Akt, also known as {{c1::protein kinase B}} (PKB), binds to {{c2::PIP3}}.
Published	08/07/2024	Akt is phosphorylated and activated by protein kinases {{c1::PDK1}} and {{c2::mTORC2}}.
Published	08/06/2024	Active Akt phosphorylates targets, including negative regulators of cell survival, and inactivates them, which prevents {{c1::cell death}}.
Published	08/07/2024	In the absence of growth factors, FOXO transcription factors translocate to the {{c1::nucleus}} and induce transcription of genes leading to cell {{c2…
Published	08/07/2024	In the presence of growth factors, FOXO is phosphorylated by Akt and sequestered in the {{c1::cytoplasm}} bound to 14-3-3 protein.
Published	08/07/2024	PTEN is a phosphatase that removes phosphates added by PI-3 kinase, thus {{c1::stimulating}} cell death and inhibiting {{c2::survival}}.
Published	08/07/2024	mTOR is a protein kinase that regulates cell growth by coupling protein synthesis to growth factors, {{c1::nutrients}}, and energy availability.
Published	08/07/2024	mTORC2 phosphorylates and activates {{c1::Akt}}.
Published	08/07/2024	mTORC1 regulates protein synthesis and acts as a sensor integrating positive signals like {{c1::growth factors}} and negative signals such as {{c2::hy…
Published	08/07/2024	mTORC1 is active when bound to Rheb-{{c1::GTP}} and inactive when bound to Rheb-{{c2::GDP}}.
Published	08/07/2024	TSC complex (TSC1/TSC2) inhibits mTOR by activating its {{c1::GTPase}} activity, leading to hydrolysis of GTP on {{c2::Rheb}}.
Published	08/07/2024	Positive signals cause TSC complex to be {{c1::phosphorylated}}, inactivating its GAP activity, which allows Rheb to bind {{c2::GTP}} and activate mTO…
Published	08/07/2024	TSC is regulated by {{c1::AMP-activated}} kinase (AMPK), which activates TSC and inhibits mTOR when the AMPratio is {{c2::high}}.
Published	08/07/2024	mTOR phosphorylates S6 kinase, which in turn phosphorylates ribosomal protein S6, increasing the rate of {{c1::translation}} elongation.
Published	08/07/2024	mTOR also phosphorylates eIF4E-BP1, which when {{c1::phosphorylated}}, dissociates from eIF4E, allowing {{c2::translation}} to proceed.
Published	08/06/2024	mTORC1 is inhibited by {{c1::rapamycin}}, an antibiotic used in organ transplants and lung cancer treatments.
Published	08/06/2024	Defects in TSC proteins lead to tuberous sclerosis, characterized by benign tumors forming throughout the {{c1::body}}.
Published	08/07/2024	The TGF-β/Smad pathway involves TGF-β receptors that are {{c1::serine/threonine}} kinases and include type {{c2::I}} and type {{c3::II}} polypeptides.
Published	08/07/2024	In the TGF-β/Smad pathway, type II receptors {{c1::phosphorylate}} type I, which then {{c2::phosphorylates}} Smad transcription factors.
Published	08/07/2024	Once phosphorylated, Smad translocates to the {{c1::nucleus}} and stimulates the expression of {{c2::target genes}}.
Published	08/06/2024	The NF-κB family of transcription factors is crucial for immune system function and is activated by the degradation of {{c1::inhibitor}} proteins.
Published	08/07/2024	In unstimulated cells, NF-κB is bound to inhibitor IκB. When TNF binds to its receptor, IκB kinase {{c1::phosphorylates}} IκB, leading to its {{c2::ub…
Published	08/06/2024	After IκB degradation, NF-κB {{c1::enters}} the nucleus and induces transcription of {{c2::target genes}}.
Published	08/07/2024	Notch signaling controls cell fate through {{c1::cell-cell}} interactions and is activated by binding of the ligand Delta on adjacent cells.
Published	08/07/2024	Ligand binding leads to Notch being cleaved by protease {{c1::γ-secretase}}, and the intracellular domain then translocates into the {{c2::nucleus}}.
Published	08/07/2024	In the nucleus, the intracellular domain of Notch interacts with transcription factor {{c1::CSL}}, converting it from a repressor to an {{c2::activato…
Published	08/07/2024	Notch signaling induces expression of {{c1::transcriptional regulatory}} proteins, influencing cell fate decisions.
Published	08/06/2024	Signaling pathways are regulated by {{c1::feedback loops}} to control the {{c2::duration}} and magnitude of the pathways.
Published	08/06/2024	Signaling pathways interact with each other to {{c1::integrate}} and {{c2::coordinate}} their activities.
Published	08/06/2024	In the NF-κB pathway, a negative feedback loop exists where NF-κB stimulates transcription of {{c1::IκB}}, which then inhibits NF-κB.
Published	08/06/2024	The ERK and PI 3-kinase pathways {{c1::interact}} with each other, where Ras activates {{c2::PI 3-kinase}}.
Published	08/06/2024	Akt inhibits {{c1::Raf}}, while ERK inhibits {{c2::TSC}} in the signaling network.
Published	08/07/2024	ERK activates {{c1::mTORC1}}, integrating the signaling from the ERK pathway into the mTORC1 pathway.
Published	08/06/2024	An {{c1::agonist}} is a drug that activates a {{c2::receptor}}.
Published	08/07/2024	An {{c1::antagonist}} is a drug that prevents the {{c2::activation}} of a receptor.
Published	08/06/2024	Supersensitization occurs when an antagonist reduces the number of receptors, leading to a {{c1::large}} increase in receptor number upon {{c2::withdr…
Published	08/06/2024	In supersensitization, there is an {{c1::increased}} response to ligand binding after the antagonist is withdrawn.
Published	08/06/2024	Desensitization occurs when an agonist reduces the number of receptors on the {{c1::surface}}, leading to a {{c2::decreased}} response to ligand bindi…
Published	08/06/2024	{{c1::hydrophobic}} signals can pass through the plasma membrane while {{c1::hydrophillic}} ones need pathways
Published	08/06/2024	{{c1::Glutamate}}, {{c1::GABA}}, and {{c1::Acetylcholine}} are not only through G- protein receptors but also act through {{c1::ionotropic}} rece…
Published	08/06/2024	{{c1::}} enhances G protein activity while {{c2::GDI}}, {{c2::GAP}}, and {{c2::RGS}} decrease it
Published	08/07/2024	Even though you can have an adgernergic receptor that responds to norepinephrine, depending on the specific adrenergic receptor of the …
Published	08/07/2024	Compare and contrast Ionotropic vs Metabotropic Signaling. {{c1::Ionotropic: Direct, fast, short-term. Opens ion channels.Metabotropic: Indirect,…
Published	08/07/2024	There is tremenous signal {{c1::amplication}} by the cAMP pathway
Published	08/07/2024	{{c1::Kinases}} are enzymes that add phosphates, and this is called {{c1::phosphorylation}}{{c1::Phosphatases}} are enzymes that remove phosphate…
Published	08/07/2024	Cells respond to {{c1::extracellular signals}} by initiating a series of steps in different pathways that lead to a {{c2::response}}.
Published	08/07/2024	{{c1::Steroid hormones}} diffuse across the plasma membrane and bind to {{c2::nuclear receptors}}.
Published	08/07/2024	{{c1::G protein-coupled receptors (GPCRs)}} transmit signals via G proteins, which are {{c2::heterotrimers}} of α, β, and γ subunits.
Published	08/07/2024	When a ligand binds to GPCRs, {{c1::GTP}} replaces {{c2::GDP}} on the α subunit of the G protein.
Published	08/07/2024	The activated Gα and Gβγ subunits can interact with their {{c1::targets}}.
Published	08/07/2024	A major target of G proteins is {{c1::adenylyl cyclase}}, which forms {{c2::cAMP}} from ATP.
Published	08/07/2024	{{c1::cAMP}} activates {{c2::PKA}}, which can phosphorylate enzymes and transcription factors.
Published	08/07/2024	Receptor tyrosine kinases {{c1::autophosphorylate}} on tyrosine after binding of ligands such as {{c2::growth factors}}.
Published	08/07/2024	Nonreceptor tyrosine kinases activate {{c1::intracellular tyrosine kinases}}.
Published	08/07/2024	The {{c1::JAK-STAT pathway}} activates transcription in {{c2::immune cells}}.
Published	08/07/2024	{{c1::Src}} is an important intermediary {{c2::signaling protein}}.
Published	08/07/2024	{{c1::MAP kinases}} are important in cell growth and are activated by {{c2::Ras}}.
Published	08/07/2024	The {{c1::PI-3 kinase/Akt pathway}} is a cell survival pathway.
Published	08/07/2024	{{c1::mTORC1}} regulates {{c2::protein synthesis}}.
Published	08/07/2024	{{c1::TGF-β}} is a serine-threonine kinase that activates {{c2::Smad}}, a transcription factor.
Published	08/07/2024	The {{c1::NF-κB}} transcription factor is activated by degradation of an {{c2::inhibitor}}.
Published	08/07/2024	Signaling pathways {{c1::interact}} with each other.
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