CS - L2

Question 1

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

Answer 1

intracellular receptors
ion coupled channels
transmembrane receptors

Question 2

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

Answer 2

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

Question 3

Describe the interactions of intracellular receptors

Answer 3

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

Question 4

How fast is the response by communication via intracellular receptors?

Answer 4

relatively slow

Question 5

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

Answer 5

transmembrane pores, MULTIPLE proteins

Question 6

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

Answer 6

ions, Na+, Cl-, Ca2+.

Question 7

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

Answer 7

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

Question 8

How fast is the response by communication via intracellular receptors?

Answer 8

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

Question 9

Why can’t most signal molecules cross plasma membrane?

Answer 9

large and/or hydrophilic

Question 10

What is the cell surface receptor structure

Answer 10

???

Question 11

What are the two common strategies used to transfer signals

Answer 11

conformational changes & clustering

Question 12

What are the three main classes of transmembrane receptors?

Answer 12

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

Question 13

Describe the 7 transmembrane G-protein coupled receptors

Answer 13

Coupled with large protein G

Question 14

What sort of activity do enzyme-linked receptors have?

Answer 14

Catalytic activity

Question 15

Do cytokine receptors have any catalytic activity

Answer 15

No

Question 16

What are cytokine receptors coupled with

Answer 16

intracellular enzymes

Question 17

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

Answer 17

G protein coupled receptors

Question 18

How many isoforms do GCPR’s have

Answer 18

800

Question 19

How many transmembrane alpha helices does GCPR have

Answer 19

7

Question 20

How many loops bind the ligand?

Answer 20

3

Question 21

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

Answer 21

Conformational change

Question 22

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

Answer 22

G protein is activated

Question 23

What does the G protein act as?

Answer 23

On/off switch.

Question 24

When is G protein active

Answer 24

If GTP is bound to G protein

Question 25

How can GPCR amplify the signal

Answer 25

GPCR can interact with multiple G proteins

Question 26

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

Answer 26

3

Question 27

What are the three subunits?

Answer 27

alpha, beta and gamma

Question 28

What is G protein bound to when inactive?

Answer 28

GDP

Question 29

What happens to GDP after GPCR binds to its ligand

Answer 29

GDP replaced by GTP, making G protein active

Question 30

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

Answer 30

Beta and gamma

Question 31

What does protein alpha subunit do after GTP replaces GDP?

Answer 31

migrates to target protein, activating target protein

Question 32

Give an example of GPCR-ligand interaction

Answer 32

epinephrine receptor - response to stress

Question 33

What is the ligand in epinephrine receptor - response to stress

Answer 33

epinephrine (adrenaline)

Question 34

What is epinephrine secreted by?

Answer 34

Adrenal glands

Question 35

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

Answer 35

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

Question 36

What sort of ligands do RTK bind to

Answer 36

growth factors and hormones

Question 37

How many membranes do RTK span

Answer 37

1

Question 38

What does the cytoplasmic side of the RTK consist of

Answer 38

tyrosine kinase domain

Question 39

what are the 2 forms of RTK

Answer 39

Monomeric inactive Dimeric active

Question 40

What does autophosphorylation do?

Answer 40

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

Question 41

What can receptor tyrosine kinase trigger?

Answer 41

multiple signal transduction pathways

Question 42

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

Answer 42

MAP kinase, AKT signalling and PLC-gamma mediated signalling

Question 43

What are the RTK activatin steps

Answer 43

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

Question 44

What is EGF

Answer 44

epidermal growth factor

Question 45

What is EGF involved in?

Answer 45

angiogenesis, apoptosis, cell proliferation, metastasis

Question 46

What sort of receptor does EGF interact with

Answer 46

RTK

Question 47

What are the common reasons behind

Answer 47

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

Question 48

What are cytokine receptors activated by

Answer 48

cytokines/GF

Question 49

What do cytokine R do?

Answer 49

control synthesis and release inflammatory mediators

Question 50

What are the three main components of cytokine receptors

Answer 50

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

Question 51

What does the receptor do?

Answer 51

Binds to ligand & R forms a dimer

Question 52

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

Answer 52

phosphorylates - itself, R and STAT= activating STAT

Question 53

What do STATs do

Answer 53

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

Question 54

What is leptin

Answer 54

a hormone - statiety hormone

Question 55

What is leptin made by

Answer 55

adipose tissue

Question 56

What is the impact of leptin

Answer 56

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