Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

PDA Block 1 > Signal Transduction > Flashcards

Signal Transduction Flashcards

1
Q

Why is Signal Transduction important?

A

In a multicellular organism, cells need to respond to signals in order to communicate with each other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do cells receive and respond to signals?

A

Cells receive signals by interacting with cellular signaling molecules which transduce the signal and induce a response to the signal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Signaling by secreted molecules (4 types)

A
  1. Paracrine signaling: Local mediators are secreted by the signaling cell and received by surrounding target cells
  2. Autocrine signaling: mediators are secreted and received by the same cell
  3. Synaptic signaling: Neurotransmitters are secreted by the pre-synaptic cleft and are received by the post synaptic cell
  4. Endocrine signaling: Hormones are secreted into the blood stream
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Signaling by plasma membrane bound molecules

A

Signaling molecule is a transmembrane protein

Target cell in direct contact with signaling cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Two major unique characteristics of intracellular steroid receptors

A
  1. These receptors are intracellular, and interact with their ligand in either the cytoplasm or nucleus
  2. These receptors are ligand-activated transcription factors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Carrier protein for cortisol

A

Corticosteroid-binding globulin (CBG)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Three parts of a steroid receptor

A

1) Hormone binding site
2) DNA binding domain
3) Transcription-activating domain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

In the basal state, GR receptors are found in the _______

Thyroid and retinoid receptors are found in the _______

A

Ctyoplasm; Nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

GRE (Glucocorticoid-response element)

A

glucocorticoid response element - A DNA sequence that binds steroid receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

GR (Glucocorticoid receptor) in basal state

A

Exists as an inactive complex in the cytosol associated with HSP90 and other cytosolic (inhibitory) proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Membrane Receptors

A

Ion Channel-Linked Receptor
G-Protein Coupled Receptor
Enzyme Linked Receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Receptors for acetylcholine, GABA, serotonin, and glycine have __ subunits, and receptors for glutamate have __ subunits

A

5;4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Nicotinic Acetylcholine Receptor = the first ion channel to:

A

1) Be purified
2) Have its sequence determined
3) Be reconstituted in a lipid bilayer
4) Provide a single channel recording

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Nicotinic Acetylcholine Receptor Function

A

Consists of 5 subunits

Binding of ACh to the α subunits opens the channel causing influx of cations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Location of Nicotinic Acetylcholine Receptors

A

Neuromuscular Junction
Peripheral autonomic nervous system
Central Nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

GABA Receptor-Gated Cl- channels

A

Primary postsynaptic inhibitory transmitter in CNS

GABA binds receptor → CL- channels open → Influx of CL- into cell → Hyperpolarization and inhibitory response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

G-protein coupled receptor passes through the plasma membrane ______ times

A

7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

3 Parts of G-protein coupled receptor

A

Receptor provides specificity
Herterotrimeric G protein is the transducer (GTP-bound and GDP-bound states)
Effector provides the catalytic component to generate the second messenger

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Heterotrimeric G Proteins

A

Three types of subunits (α,β, and γ) which function as a dimer
Gα: binds GTP and interacts with effectors (Hydrolyzes GTP→ GDP)
Gβγ: inhibits Gα; anchors to membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Different Gα subunits:

A

Gαs (stimulates adenylyl cyclase)
Gαi (inhibits adenylyl cyclase)
Gαq (activates phospholipase C)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Enzyme Linked Receptors

A

Tyrosine Kinase-Linked
Serine/threonine kinase-linked
Protein phosphatase-linked
Guanylyl cyclase-linked

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Tyrosine Kinase-Linked Receptors

A

EGF (Epidermal growth factor) Receptor: Inactive is monomer; active is dimer
PDGF (Platelet-derived growth factor) Receptor: Inactive is monomer; active is dimer
Insuling Receptor: Inactive is dimer, active is tetramer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

EGF Receptor: Ligand binding causes…

A

Dimerization
Activation of cross autophosphorylation
Binding of intracellular signaling molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

4 classes of major receptors that are major drug targets

A
  1. Intracellular steroid receptors
  2. Ion Channel-linked receptors
  3. G Protein-coupled receptors
  4. Enzyme linked receptors
25
Transcription factors (CREB)
Proteins that bind DNA and regulate (either promote or inhibit) the transcription of genes
26
Activated transcription factors induce transcription by activating __________
RNA polymerase
27
Protein Kinases
Catalyze the addition of a phosphate group to the side chain of amino acids in proteins and peptides
28
Serine/threonine-specific protein kinases
PKA, PKC, Ca(2+)/calmodulin-dependent kinase, MAP kinase (such as ERK, JNK, or p38 kinase)
29
Tyrosine-specific protein kinases
Tyrosine kinase-linked receptors (e.g. EGF receptor) and cytoplasmic kinases such as Src and Abl
30
Dual specificity kinases
Can phosphorylate both threonine and tyrosine: Map kinases kinases (MKK1)
31
Protein phosphatases
Catalyze the cleavage of a phosphate group from the side chain of amino acids in proteins and peptides (less variety than protein kinases)
32
How are the activities of protein kinases and protein phosphatases regulated
Second messengers
33
Second messengers
Small, diffusable molecules that are generated in response to ligand-receptor interactions and activate downstream effectors
34
Cyclic adenosine monophosphate (cAMP)
Generation: when Gαs activates adenylyl cyclase (activated adenylyl cyclase converts ATP to cAMP) Effector: cAMP activates Protein Kinase A
35
Diacylglycerol (DAG) and Inositol Triphosphate (IP3)
Generation: made when Gαq activates phospholipase C (PLC) - cleaves PIP2 to DAG and IP3 Effectors: DAG activates PKC; IP3 binds to IP3 receptors of ER - releases calcium
36
Ca(2+)
Generation: Generated by opening of ion channels Effectors: Binds to proteins and activates PKC and other kinases and enzymes
37
cAMP pathway
1) Binding of ligand to GPCR activates Gαs 2) Active Gαs-GTP binds to adenylyl cyclase and activates it 3) Each activated adenylyl cyclase generates many cAMP molecules from ATP 4) cAMP molecules activate protein kinase A (PKA) 5) Each activated PKA can phophorylate and activate many copies of substrate X 6) Each copy of Substrate X may activate many copies of the next downstream substrate
38
How is PKA activated
cAMP binds to regulatory subunits and releases catalytic subunits
39
GPCRs coupled to Gαq regulate the ______-______ pathway
Inositol-lipid
40
Inositol-lipid pathway
1) Ligand activates a GPCR 2) Gαq is activated by binding GTP 3) PLC is activated by binding Gαq-GTP 4) Active PLC cleaves PIP2 into IP3 and DAG 5) IP3 diffuses into the cytoplasm and causes Ca (2+) release from ER 6) DAG remains in the membrane and activated PKC 7) Ca(2+) binds to calmodulin and activates Ca(2+)/calmodulin dependent kinase
41
Monomeric G proteins
Activated by interacting with proteins known as "guanine nucleotide exchange factors" (GEFs) Inactivated by interacting with proteins known as "GTPase activating proteins" (GAPs)
42
Difference between heterotrimeric and monomeric G proteins
1) Heterotrimeric G proteins (Gα subunit) are activated by direct interaction with a GPCR (EGFR) 2) Monomeric G proteins (such as Ras) are activated by direct interaction with a GEF (SOS)
43
GEFs are activated when they are recruited to activated tyrosine kinase-linked receptors by _______ ________
Adaptor proteins (GRB2)
44
Activation Cycle of Ras (and other monomeric G Proteins)
1) Ras interacts with a GEF, which causes Ras-GDP to release its bound GDP and bind GTP, resulting in formation of active Ras-GTP 2) Active Ras-GTP binds and signals to other molecules 3) Ras has intrinsic GTPase activity and hydrolyzes bound GTP to GDP 4) Upon association with GAP, Ras-GTP hydrolyzes to inactive Ras-GDP 5) Ras-GDP is inactive until a new signal causes it to associated with a GEF
45
Ras-GTP activates the ____ ______ signaling cascade
MAP kinase
46
MAP kinase signaling cascade
Ras-GTP activates Raf (MKKK) Raf phophorylates MKK1 MKK1 phosphoylates ERK (MAP kinase) ERK phophorylates many different transcription factors
47
Gefitinib and Erlotinib
Drugs that target the kinase domain of the EGF receptor and inhibit signaling by the EGF receptor
48
Gefitinib and Erlotinib decrease lung tumor burden in ___ of patiens who have mutated EGF receptor These drugs are effective in only ___ of patients w/o receptor mutations
80%; 10%
49
EGF receptor mutations occur more frequently in
Female patients of Asian descent who have never smoked
50
Attenutation of signaling is accomplished by:
Ligand inactivation or dissociation from the receptor Receptors dissociate from other proteins Adaptor protein complexes dissociate G-proteins hydrolyze GTP to the GDP inactive state Phophorylated proteins are de-phophorylated Second messengers are metabolized or diffuse away Ions are sequestered or pumped out
51
Adaptation
Receptor-mediated endocytosis | Occurs when signaling system responds to the intensity and frequency of stimulation
52
Coated-pits (formed by clathrin)
Specialized inward-curved membranes where receptor-mediated endocytosis occurs
53
CURL
Compartment of Uncoupling of Receptor and Ligand (these vesicles have low pH (4.5-5) to favor dissociation of ligand)
54
Retroendocytosis
Dissociated ligands incorporate into vesicles and are recycled
55
Homologous desensitization
Signaling by the receptor is attenuated - can occur due to covalent modification of the ligand-bound receptor
56
What two molecules work together to desensitize GPCR
phosphorylation by β-adreneregic kinase (βark) followed by binding of β-arrestin to phosphorylated receptor
57
How is GCPR desensitized by PKA
Stimulated receptor activates PKA, the activated PKA can phosphorylate the receptor and desensitize it
58
Heterologous desensitization
Signaling by both the stimulated receptor and by other different types of receptors is attenuated: Both stimulated and unstimulated receptors are blocked

PDA Block 1 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions