Intracellular signaling flashcards

Question 1

Agonist

Answer 1

Molecule that activates responses associated with occupation of receptor

Question 2

Antagonist

Answer 2

Molecule that prevents responses associated with occupation of receptor

Question 3

Angiotension II receptor antagonists

Answer 3

Lower peripheral blood pressure

Question 4

Glucagon-like peptide receptor agonist

Answer 4

Increases insulin secretion

Question 5

2 types of receptors for secreted molecules

Answer 5

1. Cell surface receptors 2. Intracellular receptors

Question 6

Cell-surface receptors

Answer 6

Used by molecules which can’t cross the membrane due to size or charge

Question 7

Integral membrane proteins

Answer 7

Cell-surface receptors which are coupled to intracellular molecules. Ligand binding to receptor initiates signal transduction cascade/pathway.

Question 8

4 things that can bind intracellular receptors

Answer 8

Hydrophobic molecules which can bind to cytosolic or nuclear proteins 1. Steroid hormones 2. Vitamin D3 3. Reinoic acid 4. Thyroid hormones

Question 9

First messenger to second messenger signaling

Answer 9

Extracellular binding is first messenger. Binding of molecule to receptor activates 1st intracellular molecule in cascade called the second messenger which activates the enzyme cascade

Question 10

4 classes of cell surface receptors

Answer 10

1. Ligand-gated ion channel 2. Enzyme-linked 3. Cytokine 4. G-protein-coupled

Question 11

Receptor tyrosine kinases

Answer 11

Amino terminal is extracellular and carboxyl terminal is intracellular and catalytic. Enzyme effector is a component of the receptor protein

Question 12

Non-receptor tyrosine kinases

Answer 12

Enzyme effector is a receptor complex

Question 13

Adenyl cyclase

Answer 13

Enzyme effector is a non-receptor integral membrane protein

Question 14

5 second messengers

Answer 14

1. Ca2+ 2. 3’,5’-cyclic AMP 3. 3’,5’-GMP 4. 1,2-diacylglycerol (DAG) 5. Inositol 1,4,5-triphosphate (IP3)

Question 15

3 amino acids which can be phosphorylated

Answer 15

1. Serine 2. Threonine 3. Tyrosine

Question 16

3 ways to terminate signal transduction

Answer 16

1. Reducing agonist (ligand) availability 2. Internalizing and degrading of agonist-receptor complex 3. Modifying receptor to inactivate it

Question 17

Receptor Tyrosine Kinase and Mitogen Activated Protein (MAP) kinase cascade steps

Answer 17

1. Receptor binds to extracellular portion of RTK 2. RTK activated by phosphorylation 3. Adapter protein activates Ras-activating protein which activates Ras with GTP 4. Ras activates MAP kinase kinase kinase with ATP 5. Activates MAP kinase kinase with ATP 6. Activates MAP kinase with ATP 7. Nuclear gene regulatory protein OR cytosolic/membrane protein phosphorylated 8. Changes in gene expression OR rapid changes in activity of cytosolic/membrane proteins

Question 18

Receptor serine-threonine kinases (3)

Answer 18

1. Stimulated by growth regulatory families 2. Mutations in these receptors result in progression of cancer 3. Regulate SMAD transcriptional factors

Question 19

Cytokine receptors

Answer 19

Lack intrinsic kinase activity. Dimerize and bond to non-receptor tyrosine kinases. Regulate STATs transcription factors

Question 20

Cytokines

Answer 20

Polypeptides which are autocrine/paracrine regulators of growth and differentiation.

Question 21

G-protein-coupled receptors (GPCR)

Answer 21

Alpha (many kinds), beta, and gamma subunits. Bind a diverse group of ligands. 7 alpha-helical transmembrane-spanning domains. Intracellular domains bind G-proteins. Activate Phospholipases and Rho GEF.

Question 22

Adenyl signal transduction

Answer 22

Causes increase/decrease in cyclic AMP depending on signal from G proteins.

Question 23

cAMP signaling 3 steps

Answer 23

1. Uses adenyl cyclase (membrane bound) to activate Protein kinase A (PKA) by converting ATP to cAMP 2. cAMP activates PKA which phosphorylates CREB 3. Activated CREB binds to CRE which targets a gene for synthesis of cytosolic or membrane protein

Question 24

Protein kinase A (PKA)

Answer 24

Contains a nuclear translocation sequence. Within the nucleus phosphorylates CREB (cAMP-responsive element binding) which binds to CRE (cAMP-responsive regulatory elements on gene promoter)

Question 25

CREB

Answer 25

Phosphorylated by PKA and binds to CRE (cAMP-responsive regulatory elements on gene promoter)

Question 26

cGMP based signal transduction

Answer 26

Regulated by guanylate cyclases (membrane-bound). 1. Binds heme and NO stimulates guanylate cyclase 2. cGMP is second messenger 3. Activation of Protein Kinase G (PKG)

Question 27

Hydroxyurea

Answer 27

Metabolizes to NO–>NO binds and activates soluble guanylyl cyclase–>Increases cGMP production–>Activates and translocates transcription factors into nulceus–>Activates HbF

Question 28

Hemolysis

Answer 28

Increases arginase and NO depletion which leads to vasculopathy. L-arginine therapy may help.

Question 29

Calcium channels

Answer 29

Many GPCRs and RTKs stimulate 1. Cellular compartments 2. Plasma membrane 3. Gating channels by IP3 (generated by Phospholipase C)

Question 30

IP3

Answer 30

Second messenger generated by Phospholipase C

Question 31

Phospholipid-based signal transduction

Answer 31

Phospholipids become docking sites for intracellular signaling proteins

Question 32

BAD

Answer 32

When BAD is inactivated by phosphorylation it inhibits apoptosis (active BAD makes cells die)

Question 33

Phospholipase C (PLC)

Answer 33

Generates IP3

Question 34

Phospholipase A (PLA)

Answer 34

Generates free fatty acids

Question 35

Phospholipase D (PLD)

Answer 35

Generates inositol, choline, or ethanolamine and phsphatidic acid

Question 36

Activation of PKA, PKC, and PKG

Answer 36

PKA: Activated by cAMP PKC: Activated by DAG or Ca2+ PKG: Activated by cGMP

Question 37

What do protein kinases regulate?

Answer 37

Gene transcription