Cell Signalling

Question 0

EC50

Answer 0

Ligand concentration that results in 50% activity of the receptors

Question 1

Kd

Answer 1

Concentration that ligand occupies 50% of receptors

Question 2

Binding vs activity

Answer 2

Hormone induces adenylyl cyclase activity in proportion to its binding ability.

Question 3

Agonist

Answer 3

Binds and activates receptor

Question 4

Antagonist

Answer 4

Bind receptor, prevents activation. Itself has no effect on receptor activity

Question 5

Partial agonist

Answer 5

Bind and activate receptor to lesser extent than agonist

Question 6

Inverse agonist

Answer 6

Binds active receptor and blocks the activity

Question 7

Rate limiting step in G proteins

Answer 7

Catalysed release of GDP

Question 8

Gs induces

Answer 8

Increase adenylyl cyclase, Ca and cAMP

Question 9

Gi induces

Answer 9

Decrease adenylyl cyclase, Ca and cAMP
Increase PLC (Ga and GBy)

Question 10

GQ induces

Answer 10

Phospholipase C

Question 11

Classification of GPCR

Answer 11

Class A - rhodopsin
Class B - secretin
Class C - glutamate
Other - adhesion R, frizzled/ taste 2

Question 12

How to measure G protein association in cells

Answer 12

FRET - Fluorescence resonance energy transfer

Question 13

Effect of cholera toxin

Answer 13

Inhibits GTPase (NAD dependent)

Question 14

Effect of pertussis toxin

Answer 14

Prevents activation of Gi by receptor

Question 15

Phospholipase C activated by two pathways

Answer 15

PTX insensitive - Gaq

PTX sensitive - Gai (direct activation by GBy, + Gai is called conditional)

Question 16

Compound that blocks inositol recycling

Answer 16

Lithium

Question 17

Molecules that can bypass receptor ligand and activate PKC

Answer 17

Phorbol

Ca ++ iodophors

Question 18

CAMP -> PKA ->

Answer 18

Activate metabolic enzymes

CREB - cAMP response element binding protein.

Question 19

Ca-calmodulin steps

Answer 19

Ca binds calmodulin. Conformational change. Binds inactive Calmodulin dependent protein kinase. Causes auto phosphorylation. Now fully active.

Question 20

RTKs regulate

Answer 20

Cell proliferation
Differentiation
Metabolism

Question 21

SH3 binds..

Answer 21

Pro line rich targets. Eg, sos

Question 22

RTK process

Answer 22

Ligand binds
Dimerisation
Trans auto phosphorylation

Question 23

Ras is required for..

Answer 23

DNA replication / entry in S phase

Question 24

GEF

Answer 24

Guanine nucleotide exchange factor

Question 25

GAP

Answer 25

GTPase activating protein

Question 26

Map kinase pathway

Answer 26

Raf binds Ras.

Raf now membrane bound. Activates MEK. Activates ERK. Activates transcription factor.

Question 27

What can stimulate Ras

Answer 27

GPCR ( PKC )
Arrestin
TKRs

Question 28

Homologous desensitization

Answer 28

Ligand stimulation causes reduced response of active receptor
GRK - G protein receptor kinases, phosphorylate ser/thr on c terminal and c3.

Question 29

Heterologous desensitization

Answer 29

Ligand stimulation causes decreased responsiveness of inactivated receptors.
PKA

Question 30

Give two formulas need for ligand hormone stuff

Answer 30

Get it right son.