Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

025. My MCM Test 2 > Receptors and Cell Signaling > Flashcards

Receptors and Cell Signaling Flashcards

1
Q

Why is cell signaling so important? Do cells talk?

A

Communication occurs between all cells. Signaling is the basis for normal cell growth, division and homeostasis.

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

What do errors in cellular signaling cause?

A

Cancer, diabetes, autoimmunity

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

Main steps in cell signaling?

A
  1. Signaling cell secretes signaling molecule (LIGAND) in response to stimulus
  2. Ligand is transported to target cell where it binds to a protein (RECEPTOR)
  3. Ligand-receptor activates or inhibits pathway (EFFECTORS)
  4. Effectors alter acitivty downstream and generate secondary messengers (particular response)
  5. Termination of signal occurs by removing Ligand/receptor or inactivation of events
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What type of signaling is Endocrine?

A

A hormone (signal) is secreted and transported by blood to a receptor far away, turning on cascade. Long-lasting 1/2 life EX: epinephrine released by adrenal medulla acts on heart muscle

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

What type of signaling is paracrine?

A

Paracine factor (signal) diffuses to neighboring target cells of a different cell type. Local signaling, short lived signals. EX: testosterone released by leydig cells induces spermatogenesis by acting on sertoli and germ cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What type of signaling is autocrine?

A

releases signal which bind to a receptor on the same cell, or same neighboring cells. EX: interleukin1 (chemokine) produce by T-lymphocytes promotes own replication growth factors in cancer cells

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

What type of signaling is direct/juxtacrine?

A

signal binds to receptor cell, which binds the two cells together. EX: heparin-binding epidermal growth factor binds to EGF receptor. immune cells

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

What are the two types of signals?

A

hydrophilic (water soluble) and lipophilic (fat/lipid soluble)

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

Characteristics of hydrophilic signaling, ex: epinephrine, insulin, glucagon?

A

They cannot penetrate the membrane, so bind to receptors on cell surface.. activating secondary messenger, engaging proteins to a cellular response. GPCRs & RTKs

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

Characteristics of lipophilic signaling (ex: steroid/thyroid hormones, retinoids)?

A

They CAN pass through membrane, binds to receptor in cell. Ligand/receptor acts as transcription factor TF.

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

Where are lipophilic receptors located?

A

Inside the cell, either in the cytoplasm or nucleus

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

How do cytoplasmic receptors get the signal to the nucleus for lipophilic ligands?

A

The ligand binds to an inactive complex bound to HSP90. When bound, HSP90 dissociates and receptor-complex moves to nucleus where binds to HRE (hormone response element) in promoter area of genes

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

How do nuclear receptors work?

A

They are already present in the nucleus bound to DNA, hormone (ligand) activates the complex.

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

How long are the half lives of lipophilic signals?

A

LONG half - lives (hours to days)

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

What are the three types receptors?

A

ligand-gated ion channels (GABA), G protein-coupled receptors, enzyme-coupled receptor: receptor tyrosine kinases (RTKs)

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

What type of protein does GPCR signaling involve, and how many proteins are in the transmembrane domain?

A

GPCR involve heterotrimeric G proteins (three subunits alpha, gamma, beta). There are 7 transmembrane integral proteins.

17
Q

What is the generic sequence of events for GPCR signaling?

A

Ligand to GPCR on membrane to trimeric G protein to effector enzyme (act/inact) to 2nd messenger to target of messenger to biologic response

18
Q

What is the main difference between monomeric and trimeric proteins?

A

Trimeric contain GEF (fuanine nucleotide exchange factor) in the complex, monomeric have to recruit them.

19
Q

Specifically, what happens when a ligand binds to a GPCR which then binds to the G protein?

A

The now active Gprotein will exchange the GDP bound to its alpha for GTP, by using guanine exchange factor (GEF). this will separate GTP-alpha SU from beta and gamma. AlphaGTP will bind effector that produce 2nd messenger

20
Q

What percent of drugs work by GPCR?

A

70%

21
Q

What is the sequence and main contributors to Gs (activation of adenylate cyclase (AC)), used by histamine and epinephrine?

A

Ligand to GPCR, Gs GTPAlpha binds AC (+effector), produces cAMP (2nd messenger), binds PKA, activates. Phosphodiesterase (PDE) removes 2nd messenger & turns off

22
Q

What is the sequence and main contributors to Gi (inhibits adenylate cyclase (AC)), used by epi/norepi/dopamine?

A

Ligand to GPCR, Gi GTPalpha binds AC (-effector) , inhibits cAMP production & PKA activation

23
Q

What is the sequence and main contributors to Gt (stimulates cGMP phosphodiesterase(PDE))?

A

LIGHT to GPCR (rhodopsin), Gt GTPalpha binds cGMP PDE, turns cGMP to 5’-GMP, turning off. no light = turned on

24
Q

What is the sequence and main contributors to Gq (activates phospholipase C), used by acetylcholine?

A

Ligand to GPCR, Gq GTPalpha binds phospholipase C, which breaks PIP2 into DAG and IP3. DAG to PKC (phosphorylation to alter protein activity) IP3 to ER, opens Ca channels, releasing Ca2+, activating calmodulin-dependent proteins

25
Q

What is so important of epinephrine and Gs?

A

Epinephrine non-selective agonist of all adrenergic receptors. undergo multiple GPCR signaling pathways

26
Q

How does signal desensitization (ability to turn off or ignore signal) work?

A
  1. remove ligand
  2. ligand (hormone) levels drop leading to decreased activity
  3. receptor sequestration :endosome pulls inside
  4. receptor destruction by endosomes and lysosomes
27
Q

What is GAP and what does it do?

A

GAP is GTPase activating protein, it will turn off GTP-alpha if GTP and alpha do not turn off and dissociate on their own

28
Q

What are G protein receptor kinases GRKs and arrestin and what do they do?

A

GRKs phosphorylate activated GCPRs using ATP, arrestin binds to phosphorylation and inhibits GDPalpha from getting converted into GTPalpha = inactivated GPCR

29
Q

What are the main components of receptor tyrosine kinase RTK?

A

ECD which binds to signal
Single alpha helical trasnmembran domain
ICD with tyrosine kinase activity

30
Q

What is the first step of RTK signaling?

A

Ligand, usually growth factors (EDF, insulin) bind to receptor and cause dimerization

31
Q

What happesn when dimerization of the receptor in RTK occurs?

A

the dim receptor phosphorylates tyrosine residues and these phosph-tyrs are recognized by adaptor and docking proteins which activate downstream signaling (RAS)

32
Q

What are the two types RAS s in RTK signaling and what do they do?

A

RAS-dependent linked to MAPK path
RAS-independent linked to other kinases
Trigger phosphorylation of specific protein targets in cyto/nucl

33
Q

What is the final product of RTK and how is RTK signal terminated?

A

RTK leads to gene transcription and protein activity degredation of ligand, RAS inactivation, endocytosis, deposphorylation

34
Q

How is RAS activated and inactivated?

A

GEF uses GTP to activate RAS, GAP dephosphorylates back to GDP, inactive

025. My MCM Test 2 (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions