Brainscape's Knowledge GenomeTM

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


See full index

MCM Quiz2 > Receptors and signalling > Flashcards

Receptors and signalling Flashcards

1
Q

what is endocrine signalling?

A

signal (hormone) is transported via blood

Ex: epinephrine is released by adrenal medulla to go to heart
“Long lasting

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

what is paracrine signalling?

A

Signal (paracrine factor) diffuses to
neighboring cell of a different type

Ex: testosterone made in Leydig cells induce spermatogenesis in Sertoli & germ cells
“Short-lived” signal

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

what is autocrine signalling?

A

secreting cells express surface receptors
for the signal. Same cell - uses receptors on own
surface
Ex: interleukin-1

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

what is juxtacrine signalling?

A

signal binds to signaling cell which then
binds to receptor on adjacent target cell.

Ex: heparin-binding epidermal growth factor
Binding to EGF receptor
Immune cells

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

what do lipophilic signals do and what is their significance?

A

Able to pass through plasma membrane

Binds to specific intracellular receptor proteins in cytosol or nucleus

several families of DNA binding transcription factors

long half lives

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

what are the two types of receptors that lipophilic signals target?

A

nuclear receptors

cytoplasmic receptors

both regulate transcription of genes

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

what do hydrophilic signals do and what is their significance?

A

Cannot penetrate PM

Interacts with specific receptors at cell surface

Signaling molecule-receptor complex starts production of second messenger molecules inside cell

short lived

GPCRs and RTKs

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

what are the three binding domains of GPCR?

A
  • extracellular Domain (ECD)- binds to signal
  • Transmembrane Domain (TM)- composed of 7 A-helices
  • Intracellular Domain (ICD)- interacts with G protein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how do GPCRs G activate proteins?

A

signaling exchange of GDP for GTP leading to second messenger activation

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

how does GPCR activation process work?

A

Ligand binds to receptor,

conformational change in receptor,

GPCR interacts with G proteins,

receptor acts as GEF, GDP into GTP

Ga changes and kicks out GTP for GDP,
Ga binds to and activates or inactivates effector molecule, secondary molecules

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

what subunits are a part of the trimeric g protein?

A

Alpha, Beta, Gamma

Inactive G protein has GDP bound to A-subunit

alpha bound to beta and gamma

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

What is the Gs pathway, what does it do?

A

stimulates adenylate cyclase,cAMP -> PKA (on) -> phosphorylation of downstream targets

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

What does Epi do to Gs

A

relaxes bronchial & smooth muscle of intestine

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

What does Histamine do to Gs?

A

bronchoconstriction, allergic

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

What is Gi?

A

inhibits adenylate cyclase

Adenylate cyclase (off)

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

what does Epi do to Gi?

A

constriction of smooth muscle

17
Q

What does dopamine do to gi?

A

increase HR

18
Q

what does gt do?

A

cGMP phosphodiesterase

If bound by light (vision)

19
Q

what does Gq do?

A

activates Phospholipase C (PLC)

DAG + IP3 -> CA2+ release from ER/SR -> Calmodulin complex

20
Q

What if acetylcholine binds to Gq?

A

bronchoconstriction and stimulation of salivary glands; parasympathetic NS

21
Q

Whats the significance of cholera and GPCR?

A

stops inactivation of Gs-A

ADP ribosylation of Arg, decreases GTPase activity

Gs-A stays ON causing overproduction of cAMP
cAMP abundance in GI cells open Cl- channels
Loss of water, and electrolytes due to diarrhea

22
Q

Pertussis Toxin and GPCR?

A

blocks activation of Gi-A

Blocks Gi-A from turning off Adenylate cyclase

ADP ribosylation of Cys on Gi-A prevents activation and dissociation of A-subunit

Less inhibition of AC and Overproduction of cAMP
Loss of fluids and excessive mucus in airway epithelial cells

23
Q

what is signaling desensitization?how is it done?

A

Ability to turn off or “ignore” a signal

Decreased hormone levels -> decreased adenylyl cyclase activity -> decreased cAMP -> decrease PKA activity

Removing signaling molecule: phosphodiesterase removes cAMP/cGMP

Receptor sequestration: endosome

Receptor destruction

24
Q

Hydrolysis of cyclic nucleotides, significance?

A

enzymes hydrolyze cyclic nucleotides to regulate cellular levels

cAMP phosphodiesterase: hydrolyzes cAMP to AMP
cGMP phosphodiesterase: hydrolyzes cGMP to 5’-GMP

Inhibitors of cGMP PDE increases concentration of cGMP leading to smooth muscle relaxation and vasodilation

25
Q

what is the significance of Nitric oxide and smooth muscle relaxation?

A

responsible for relaxation of smooth muscles.

NO diffuses to neighboring muscles and activates guanylate cyclase -> productions of cGMP

lower blood pressure

Pts taking nitrates should NOT take drugs that inhibit cGMP PDE (ie viagra)

extreme drops in BP

26
Q

Antihistamine and G protein-coupled receptor signaling?

A

Block binding of histamine to histamine receptor

Are lipophilic compounds

27
Q

signaling via receptor tyrosine kinases (RTK)

A

ECD contains binding site

Single helix spans membrane

ICD possesses Tyrosine Kinase Activity

28
Q

Monomeric G proteins, how do they work? steps in the process?

A
  1. Upon ligand binding to RTK, ECD dimerizes
  2. Specific tyrosine are autophosphorylated
  3. Phosphotyrosine binds to adapter and docking proteins (SH2 & Grb2)
  4. Activates downstream signaling pathway RAS dependent or independent
  5. Triggers phosphorylation of protein targets in nucleus, PM and cytoplasm -> alteration in gene transcription and protein activity
  6. RTK signaling is terminated
29
Q

RTKs and cancer , significance?

A

Target of pharmacological inhibitors due to excessive signaling from mutated/overexpressed RTKs associated with cancer

Breast cancer drug herceptin targets HER2, which belongs to EGF-binding RTKs

30
Q

Ras and cancer, significance?

A

Mutant forms of RAS, or its GEFs or GAPs have been used in human cancers

30-50% lung and colon cancer / 90% pancreatic cancers associated with activating point mutations in Ras

Mutations decrease GTPase activity and keep it active

31
Q

Insulin signalling via RTK, explain it?

A

Insulin activates RTK creating an intermediate scaffold including IRS-1

Binds to either GRB-2 (RAS-dependent) or PI3-Kinase (RAS-independent)

32
Q

What is the Ras independent pathway?

A

Alters protein and enzyme pathway to plasma membrane

Ex: activation of glycogen synthase

33
Q

What is the Ras dependent pathway?

A

Alters gene transcription:

Ex: Increased transcription of glucokinase

MCM Quiz2 (10 decks)

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