Receptor-effector coupling

Question 1

What is signal transduction?

Answer 1

Signal (hormone for example) binds to receptor - transduction - biological effect and some kind of feedback/termination..

Question 2

Earl sutherland Junior

Answer 2

1971 NP for Epinepherine/insulin. Activity was triggered by a second messenger cyclic AMP (cAMP)

Question 3

What are second messengers?

Answer 3

Intracellular molecules that change in concentration in response to extracellular signals. Free to diffuse through cell and used to amplify signals. Can communication and coordinate.

Question 4

Ligand gated ion channel

Answer 4

When NT binds, opens channel. No NT channel is closed.

Question 5

G-protein couples receptors

Answer 5

G = protein complex. Activation of G protein subunits (3) separate and can activate an effector protein or open an ion channel.

Question 6

Monomeric G-protein

Answer 6

Chemical binds to receptor there is an exchanged for GDP (Diphosphate - inactive) or GTP (triphosphate - active),
Ras - cell growth
rho - change shape/cytoskeleton
Rab - Secretion
Arf - vesciles
Ran - nuclear transport of RNA

Question 7

Heterotrimeric G-proteins

Answer 7

Three sub units making the G protein. When ligand binds exhange of GDP and GTP. G alpha subunit binds to effector proteins. Beta/gamma subunit.
GAP removes a phosphate = inactivates.

Question 8

Why is the alpha subunit so important in second messenger signalling?

Answer 8

Depending on the protein that creates the alpha subunit determines the cascade of biological responses.

Question 9

What are some of the alpha subunits?

Answer 9

Gas - activate Adenylyl cyclase
Gaq - activate phospholipase C
Gai - inhibit Adenylyl cyclase
Gat - activates guanylyl cyclase
G12/13 activate Pho GTPases

Question 10

Importance of GPCRs in pharaceuticals?

Answer 10

30% of all phamaceutial drugs targets GPCRs

Question 11

What are some of the different second messengers?

Answer 11

Hydrophilic = Cyclic nucleotides, calcium ion, inositol-1,4,5-triphosphate.
Hydrophobic = Diacylgylcerol
Gases= nitric oxide.

Question 12

What is Cyclic AMP

Answer 12

cAMP is an adenine monophosphate - created by ATP by adenylyl cyclase (remove 2 phosphates) - Gas can go and activate it.
Open ion channel or activate other kinases.

Question 13

What do phosphodiesterase enzymes do?

Answer 13

Convert cAMP back to AMP. and cGMP to GMP.

Question 14

What is cGMP?

Answer 14

Cyclic Guanine.
Gat can activate Guanine cyclase in PM which catalyses cyclation og GTP to cGMP and pyrophosphate.
Open channels or activate protein kinase G (PKG)
Phosphodiesterase enzyme convert cGMP back to GMP.