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BGM2002 > CS - L2 > Flashcards

CS - L2 Flashcards

1
Q

What are the three general strategies used to transfer information across the plasma membrane

A

intracellular receptors
ion coupled channels
transmembrane receptors

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2
Q

What sort of molecules interact with intracellular receptors - give an example

A

small, hydrophobic molecules/ (g) - steroid hormone/NO

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3
Q

Describe the interactions of intracellular receptors

A

1 form complex-ligand receptor = active = complex translocates into the nucleus where it acts as/activates a txn factor = responsive genes

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4
Q

How fast is the response by communication via intracellular receptors?

A

relatively slow

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5
Q

What are ligand-gated ion channels or Ion-coupled
channels or Ion-channel-coupled receptors?

A

transmembrane pores, MULTIPLE proteins

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6
Q

What sort of molecules interact with ligand-gated ion channels, ion-coupled channels or ion-channel-coupled receptors - give an example

A

ions, Na+, Cl-, Ca2+.

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7
Q

What is the role of ligand-gated ion channel/ion-coupled channels/ ion channel-coupled receptors

A

converts chemical signal (neurotransmitter) into electric signals (ion flow0

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8
Q

How fast is the response by communication via intracellular receptors?

A

Very rapid & transient = change in membrane potential = exciting postsynaptic target cell

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9
Q

Why can’t most signal molecules cross plasma membrane?

A

large and/or hydrophilic

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10
Q

What is the cell surface receptor structure

A

???

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11
Q

What are the two common strategies used to transfer signals

A

conformational changes & clustering

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12
Q

What are the three main classes of transmembrane receptors?

A

G protein coupled receptors, enzyme-linked receptors, cytokine receptors

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13
Q

Describe the 7 transmembrane G-protein coupled receptors

A

Coupled with large protein G

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14
Q

What sort of activity do enzyme-linked receptors have?

A

Catalytic activity

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15
Q

Do cytokine receptors have any catalytic activity

A

No

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16
Q

What are cytokine receptors coupled with

A

intracellular enzymes

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17
Q

What is the largest family of cell surface receptors in eukaryotes?

A

G protein coupled receptors

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18
Q

How many isoforms do GCPR’s have

A

800

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19
Q

How many transmembrane alpha helices does GCPR have

A

7

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20
Q

How many loops bind the ligand?

A

3

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21
Q

What sort of change does ligand binding to receptor cause in GCPR?

A

Conformational change

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22
Q

What happens as a result of conformational change after the binding of ligand to GPCR

A

G protein is activated

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23
Q

What does the G protein act as?

A

On/off switch.

24
Q

When is G protein active

A

If GTP is bound to G protein

25
Q

How can GPCR amplify the signal

A

GPCR can interact with multiple G proteins

26
Q

Heterotrimeric GTP-binding proteins are composed of how many subunits?

A

3

27
Q

What are the three subunits?

A

alpha, beta and gamma

28
Q

What is G protein bound to when inactive?

A

GDP

29
Q

What happens to GDP after GPCR binds to its ligand

A

GDP replaced by GTP, making G protein active

30
Q

What does G protein dissociate with when GDP is being replaced with GTP

A

Beta and gamma

31
Q

What does protein alpha subunit do after GTP replaces GDP?

A

migrates to target protein, activating target protein

32
Q

Give an example of GPCR-ligand interaction

A

epinephrine receptor - response to stress

33
Q

What is the ligand in epinephrine receptor - response to stress

A

epinephrine (adrenaline)

34
Q

What is epinephrine secreted by?

A

Adrenal glands

35
Q

What sort of responses are a result of epinephrine response to stress?

A

increased heart rate, dilation of blood vessels, increase in blood glucose through glycogenolysis stimulation in liver cells, inhibition of insulin release by pancreas

36
Q

What sort of ligands do RTK bind to

A

growth factors and hormones

37
Q

How many membranes do RTK span

A

1

38
Q

What does the cytoplasmic side of the RTK consist of

A

tyrosine kinase domain

39
Q

what are the 2 forms of RTK

A

Monomeric inactive
Dimeric active

40
Q

What does autophosphorylation do?

A

catalytic efficiency of the receptor and provides binding sites for the assembly of downstream signalling complexes

41
Q

What can receptor tyrosine kinase trigger?

A

multiple signal transduction pathways

42
Q

Give an example of common signalling pathways activated downstream of RTK RAF/MAP kinase

A

MAP kinase, AKT signalling and PLC-gamma mediated signalling

43
Q

What are the RTK activatin steps

A
  1. dimerisation
    bivalent ligand binds simultaneously
  2. Tyr kinase activated
    autophosphorylation of Tyr domains
  3. RTK + protein = cellular response
44
Q

What is EGF

A

epidermal growth factor

45
Q

What is EGF involved in?

A

angiogenesis, apoptosis, cell proliferation, metastasis

46
Q

What sort of receptor does EGF interact with

A

RTK

47
Q

What are the common reasons behind

A

Activating mutation
Increase gene copy number
Overexpression
Truncation of receptor EC domain

48
Q

What are cytokine receptors activated by

A

cytokines/GF

49
Q

What do cytokine R do?

A

control synthesis and release inflammatory mediators

50
Q

What are the three main components of cytokine receptors

A

receptor, JAK (janus kinase) and STAT (signal transducer & activators of txn)

51
Q

What does the receptor do?

A

Binds to ligand & R forms a dimer

52
Q

What happens to JAK after cytokine receptor after R forms a dimer

A

phosphorylates
- itself, R and STAT= activating STAT

53
Q

What do STATs do

A

dissociate from receptor, dimarise - > moves to nucleus binds to promoter region = activation of txn

54
Q

What is leptin

A

a hormone - statiety hormone

55
Q

What is leptin made by

A

adipose tissue

56
Q

What is the impact of leptin

A

reduces food intake, controls metabolism and body weight and is also involved in regulation of immune function

57
Q
A

BGM2002 (6 decks)

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