16.2

Question 1

What are the 3 main types of Cell-Surface receptors?

Answer 1

1. G Protein-Coupled Receptors
2. Enzyme-Coupled Receptors
3. Ion Channel-Coupled Receptors

Question 2

What is the largest family of cell-surface receptors?

Answer 2

G Protein-Coupled Receptors

Question 3

around how much of all drugs target GPCR?

Answer 3

50%

Question 4

GPCRs bind a variety of signals and link to different G proteins to do what?

Answer 4

activate second messenger pathways

Question 5

What do GPCRs do, in order to activate second messenger pathways?

Answer 5

bind a variety of signals and link to different G proteins

Question 6

What are GPCRs?

Answer 6

Cell surface receptors that interact with G proteins to propagate signals

Question 7

What are G Proteins?

Answer 7

Intracellular proteins acting as switches when bound to GTP/GDP

Question 8

What is Adenylyl Cyclase?

Answer 8

The enzyme catalyzing the conversion of ATP to cAMP

Question 9

What is cAMP?

Answer 9

A second messenger involved in signal transduction

Question 10

What is Phospholipase C (PLC)?

Answer 10

The enzyme generating IP3 and DAG

Question 11

What is the role of IP3?

Answer 11

Releases Ca2+ from the ER

Question 12

What is the role of DAG?

Answer 12

Activates PKC for further signaling

Question 13

What are RTKs (Receptor Tyrosine Kinases) ?

Answer 13

Cell surface receptors triggering protein cascades upon activation

Question 14

G Proteins are composed of what 3 subunits?

Answer 14

α, β, and γ

Question 15

What is the process that occurs when G proteins act at molecular switches?

Answer 15

GPCR activation triggers G protein binding, causing GDP to exchange for GTP, activating the α-subunit

Question 16

What happens to activated subunits?

Answer 16

They can dissociate and regulate target proteins; the α-subunit’s intrinsic GTPase activity controls activation duration

Question 17

What are the 2 mechanisms of G-Protein regulation?

Answer 17

Ion Channels & Membrane-bound Enzymes

Question 18

The Membrane-Bound Enzymes consist of what?

Answer 18

the activation of
- adenylyl cyclase
(which produces cAMP)
-phospholipase C
(which produces IP3 & DAG)

Question 19

What is the process of the cAMP signalling cascade?

Answer 19

G Protein Activation - Adenylyl Cyclase Activation - cAMP synthesis - PKA Activation

Question 20

cAMP Signalling Cascade leads to what?

Answer 20

rapid responses like glycogen breakdown, and can trigger gene transcription for prolonged responses

Question 21

What is the process of the IP3 and DAG signalling pathway?

Answer 21

G Protein - Phospholipase C activation - IP3 and DAG synthesis

The IP3 then triggers the release of Ca2+ from the ER, while DAG activates PKC for further signal propagation

Question 22

What is the role of Ca2+ Signalling?

Answer 22

functions as a secondary messenger involved in muscle contraction, NT release, and cell secretion through its interaction with proteins like calmodulin

Question 23

What is the largest class of Enzyme Coupled Receptors?

Answer 23

RTKs: Receptor Tyrosine Kinases

Question 24

What do RTKs do?

Answer 24

Phosphorylates tyrosine residues on intracellular proteins

Question 25

What is the structure of an Enzyme-Coupled Receptor?

Answer 25

Single transmembrane proteins with extracellular ligand-binding domain, and an intracellular enzyme-associated domain.

Question 26

How are RTKs activated?

Answer 26

through dimerization, enabling phosphorylation and recruitment of signalling complexes

Question 27

What is the Ras Protein?

Answer 27

a Monomeric GTP-binding protein, which acts as a molecular switch

Question 28

What does the Ras Protein do?

Answer 28

activates a MAP kinase cascade, which is essential for cell proliferation/differentiation; implicated in ~30% of human cancers

Question 29

What is DAG, what does it do?

Answer 29

Diacylclycerol; Activates PKC for further signaling

Question 30

What are RTKs, what do they do?

Answer 30

Receptor Kinase Receptors; Cell surface receptors that trigger protein cascades upon activation