Membrane trafficking and vesicular transport (Receptors and their signal transduction 3) Flashcards Preview

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Flashcards in Membrane trafficking and vesicular transport (Receptors and their signal transduction 3) Deck (24)
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1
Q

Receptors with tyrosine kinase activity are mostly _____ ?

A

growth factors

2
Q

What is Ras?

A

a monomeric GTP-binding protein

it is also a main regulator of growth promoting pathway

3
Q

What are the steps of the Growth Promoting Pathway?

A
  1. Ligand binding

• receptor changes configuration → dimerization

  1. Autophosphorylation → cross phosphorylate
  2. SH2 domain recognize phosphotyrosine residue
  3. Grb2 protein recruited

• adapter protein → links 2 proteins

  1. Ras GEF protein (SOS) activates Ras

• Ras-GDP → Ras GTP

Cascade begins until eventually MAP kinase is activated and goes to the nucleus

4
Q

What is the MAP-kinase cascade?

A

Ras activated MAP-kinase-kinase-kinase

MAP-kinase-kinase-kinase

MAP-kinase-kinase

MAP-kinase

5
Q

What are two intracellular noteworthy proteins (containing a SH2) that bind to an activated receptor?

A

PI-3 kinase

inhibition of apoptosis

phospholipase C gamma

can be activated by tyrosine kinase receptor

6
Q

SH2 domain can be _____ ?

A

the phosphotyrosine itself

or

surrounding of phosphotyrosine

7
Q

What is the function of PI 3 -kinase?

A

creates docking sites

PI 3 kinase phosphorylates position 3 of PI 4,5 biphosphate

producing PI 3,4,5-triphosphate

this is important because it acts as the initiating point of signaling pathways → pleckstrin homology domain

8
Q

What is PI 3,4,5-triphosphate recognized by?

A

proteins that have the domain Pleckstic Homology (PH domain)

9
Q

How is PI 3-kinase activated?

A

an extracellular survival signal activates a receptor tyrosine kinase which recruits and activates PI 3-kinase

10
Q

What is a second pathway that can be taken by PI 3,4,5 triphosphate? What is the consequence of this?

A

PI 3,4,5 triphosphate

(activates)

PDK1 or PKB (protein kinase B)

death inhibitory protein

apoptosis inhibited

consequence: increase cells without control aka cancer

11
Q

What are these cells called which are uncrontollably increasing? Examples?

A

oncogenes

  • growth factor receptors
  • Ras
  • PI 3-kinase
  • GrB2
12
Q

What are guanylyl cyclase receptors?

A

convert GTP → cGMP

Atrial Natviuretic Peptide (AND)

13
Q

How do primary messengers stimulate guanylyl cyclase?

A

cGMP

protein kinase

target proteins

OR

for soluble guanylyl cyclase

  1. regulated by: Ca 2+
  2. binds and activates NO
  3. metabolized by cGMP phosphodiesterase → 5amp
14
Q

What are serine-threonine kinase receptors?

A
  • receptor of TGF-B
  • phosphorylates and regulates SMAD-P
15
Q

What are some enzyme activity-linked receptors?

A
  • growth hormone receptor
  • prolactin
  • cytokines
16
Q

What type of ligands do intracellular receptors bind?

A

lipophillic ligands

17
Q

What are examples of hormones acting on intracellular receptors?

A
  • steroids
  • thyroid hormones
  • vitamin D3
  • retinoic acid
18
Q

What do steroid hormones stimulate?

A

the trasncription of early response genes and late response genes

19
Q

What is the relationship between the length of time which a ligand binds to a receptor?

A
  • receptors have high affinity once hormone (or some sort of ligand) binds to it
  • the longer the ligand stays, the higher the affinity
20
Q

What are the different ways of signal termination?

A
  • Ligand Dissociation
  • Arrestin
  • Receptor Internalization
21
Q

What is the function of receptor kinase in signal termination?

A

phosphorylates activated receptors

(ATP gives it’s phosphate to the recteptor)

22
Q

How does the Beta Arrestin terminate the signal?

A
  • binds to the activated phosphorylation receptor
  • G protein cannot bind to receptor any longer

this process is known as desensitivation

23
Q
A
24
Q

What is receptor internalization/ endocytosis?

A