Intracellular Signalling (session 2) Flashcards Preview

Semester 1-ICPP > Intracellular Signalling (session 2) > Flashcards

Flashcards in Intracellular Signalling (session 2) Deck (23):
1

What is signal transduction?

Transmission of molecular signals from a cell's exterior to its interior

2

What are the three superfamilies of cell surface receptor?

G protein-coupled (7TM (transmembrane)) receptors
Ligand-gated (receptor operated) ion channels
Receptors with intrinsic enzymatic activity (heterogenous receptor)

3

What are GPCR agonists?

Bind to receptor and activate it, leading to intracellular signal transduction events. Have affinity and efficacy

4

What are GPCR antagonists?

Bind to receptor but do not activate it (block effects of agonists at receptor). Have affinity but no efficacy

5

What is an example of a GPCR agonist?

Salbutamol and analgesia/anaesthesia

6

What is an example of GPCR antagonist?

Cardiovascular and neuroleptics (anti-schizophrenic)

7

What do different GPCRs respond to?

Ions (H+ and Ca2+)
Neurotransmitters (ACh, glutamate)
Peptide and non-peptide hormones (glucagon and adrenaline)
Large glycoproteins (thyroid-stimulating hormone)

8

What is the common basic structure shared by all GPCRs?

Single polypeptide chain (300-1200AAs), also called serpentine
7-TM spanning regions
Extracellular N terminal
Intracellular C terminal
Varying size of N and C

9

How do GPCRs cause change in cellular activity?

~Activated GPCR must interact with G protein
~GPCR-G protein (guanine nucleotide exchange factor (GEF)) interaction activates G protein by causing GTP to exchange for GDP on G protein alpha subunit-GTP replaces GDP because high conc of GTP in cells
~alpha-beta/gamma complex dissociates and each interact with effector proteins
~GTPase hydrolyses GTP back to GDP and alpha-GTP an beta/gamma subunits reform

10

What are the subunits that G proteins are made of?

Alpha
Beta
Gamma

(Structurally trimeric but functionally dimeric so alpha and beta/gamma)

11

Name effectors that are also enzymes

Adenylyl cyclase
Phospholipase C
PI3K
cGMP phosphodiesterase

12

Name effectors that are ion channels

Voltage-operated Ca2+ channels (VOCCs)
G protein-regulated inwardly-rectifying K+ channels (GIRKs)

13

Which reaction does adenylyl cyclase catalyse?

ATP -> cyclic AMP

14

Which reaction does phospholipase C catalyse?

PIP2 -> IP3 + DAG (diacyl glycerol)

15

Define inotropy

Force with which heart contracts

16

What is positive inotropy?

Blood-borne adrenaline and sympathetically released noradrenaline interact with ventricular beta1-adrenoceptors to increase force of contraction

17

In the CNS and PNS, what modulates neurotransmitter release?

Presynaptic GPCRs

18

Why does the "receptor -> G protein -> effector" reaction happen on the plasma membrane?

It concentrates all the components on the same domain.

19

Which Gs coupled receptors stimulate adenylyl cyclase? (3)

Beta-adrenoceptors
D1 dopamine receptors
H2 histamine receptors

20

Which Gi coupled receptors inhibit adenylyl cyclase?

Alpha2-adrenoceptors
D2 dopamine receptors
Mu opioid receptors

21

What do the R and C subunits of cAMP do?

R=regulates the C subunit
C=catalytic subunit, phosphorylates target proteins in the cell

22

What effect does IP3R activation have on cytoplasmic [Ca2+]?

Increases [Ca2+] by 5-10 fold (from 1 x 10-7 M) within a few seconds of agonist addition

23

Which Gq coupled receptors stimulate phospholipase C?

Alpha1-adrenoceptors
M1 muscarinic receptors
H1 histamine receptors