BIOL1025 - Hydrophilic signalling - G-protein linked receptor

Question 1

orphan receptor

Answer 1

unknown

Question 2

G-protein receptor

Answer 2

superfamily of around 800 protein in human genome

Question 3

structure of G-protein

Answer 3

has 7 pass structure - start N-terminus out of cell and end C terminus

Question 4

roles

Answer 4

senses
neurotransmission
hormone secretion
chemotaxis etc

Question 5

trimetric G-protein - large protein

Answer 5

a, b, y

Question 6

a

Answer 6

has GTP and GDP binding and GTPase activity - GTP to GDP

GTP bind active signalling forming complex GDP - inactive

Question 7

larges G protein

Answer 7

link to inner membrane associated with receptor

Question 8

signal transduction by G-protein (inactive state)

Answer 8

GPCR bound to G-protein - if GTP -outer subunit then signal stops
ligand binds at extracellular of GPCR causing conformational change in receptor transmitted to Ga subunit to release GDP exchanging for GTP
which dissociates from Gby dimer and receptor - both active complex

Question 9

when active

Answer 9

Ga and Gby causes signalling effects

Question 10

no. of Ga

Answer 10

20
depends on form = different signalling events
Gas, Gai, Gaq

Question 11

no. Gb

Answer 11

5

some can interact with ion channels

Question 12

no. Gy

Answer 12

13

Question 13

when active there are differences in … due to specificity to signals

Answer 13

expression pattern
receptor binding
effects produced in cells

Question 14

target of activated Gas-subunit

Answer 14

activate GPCR by noradrenaline bind to receptor activates adenylyl cyclase
converting ATP to cAMP activating PkA by binding of cAMP to regulatory subunit of PkA by release catalytic subunit

Question 15

PkA

Answer 15

protein kinase A - phosphorylating function

Question 16

GPCR

Answer 16

G-protein coupled receptor

Question 17

cAMP

Answer 17

cyclic AMP

Question 18

formation of cAMP from ATP

Answer 18

by adenylyl cyclase - removing 2 phosphate groups = cyclic reaction between O and C3 and C5r = cAMP

Question 19

cAMP phosphodiesterase function

Answer 19

break down = inactive monophosphate (5’ AMP)

Question 20

example of Gas-subunit

Answer 20

beta adrenergic receptor

for signalling for neurotransmitter adrenaline

Question 21

B adrenergic receptor activated PkA

Answer 21

fast or slow

Question 22

fast activated PkA

Answer 22

phosphorylate and activate other enzymes

Question 23

slow activated PkA

Answer 23

bind to DNA regulating enzyme and transcription

Question 24

some prostaglandin receptors

Answer 24

a of activated GP inactivates adenylyl cyclase
receptor binds to GP
Gai binds to adenylyl cyclase and deactivates it decreasing in cAMP
PkA inactivates

Question 25

Gaq subunit

Answer 25

activated Gaq released - move around and activate phospholipase C
targets PIP2 cleaves = IP3 + DAG

Question 26

example of Gaq

Answer 26

Antidiuretic hormone

Question 27

PIP2

Answer 27

phosphatidylinositol-4,5-bisphosphate

Question 28

PC

Answer 28

phospholipase C

Question 29

PkC

Answer 29

Protein kinase C

Question 30

acetylcholine can activate 2 signalling pathways activating PC

Answer 30

IP3

Ca2+

Question 31

IP3

Answer 31

inositol 1,4,5 triphosphate
binds to Ca2+ in ER
increasing cytoplasmic [Ca2+] from 0.1 to 10 um

Question 32

IP3 - activating PkC

Answer 32

activates no. protein targets including transcription

terminated by conversion to inactive metabolite

Question 33

Ca2+ pathway

Answer 33

intracellular messenger
no. cellular process produced by Ca2+ increases and binds to calmodulin = conformational changes - bind protein
act as a switch

Question 34

termination of Ca2+

Answer 34

by ER pump - pumps Ca2+ back into ER

Question 35

example of calmodulin

Answer 35

CaM - kinase - calmodulin dependent kinase