Lecture 1/19 - Signalling

Question 1

Paracrine factors

Answer 1

Type of signalling. Local factors that do not require blood supply

Question 2

Endocrine hormones

Answer 2

Type of signalling. Must travel in the blood from one organ to another organ

Question 3

Neurotransmitters

Answer 3

Type of signalling. Travels across a synapse (nerve-to-nerve or nerve-to-muscle)

Question 4

Autocrine factors

Answer 4

Signals which act on their own tissue

Question 5

Ligand-gated Ion Channels

Answer 5

A ligand (e.g. acetylcholine) opens the gate to the ion channel (e.g. Na+)

Question 6

G Protein-Coupled Receptors (GPCR)

Answer 6

Receptors that activate G-proteins by binding GTP. Includes 7TM.

Question 7

Signal transduction

Answer 7

How we can get a signal to make a response. Between reception and response.

Question 8

Receptor Tyrosine Kinases

Answer 8

Phosphorylates itself and target proteins

Question 9

7TM

Answer 9

Similar to bacteriorhodopsin (7 helixes that go back and forth within the membrane) with ligand bound in the middle. Doesn’t pump protons. Mediates many different biological functions. Each thing we smell has its own G-protein receptor. One ligand is epinephrine

Question 10

second messengers

Answer 10

cAMP, cGMP, and PI3 and diacylglycerol (DAG). When cAMP clipped, forms 5’ AMP which serves to terminate the response of GPCR

Question 11

Calmodulin

Answer 11

A protein that modulates activities in the presence of calcium

Question 12

Name the enzyme which reverses the covalent modification
and the consequence of insulin signaling causes in a reversal of the covalent modification that resulted from
epinephrine signaling

Answer 12

Protein phosphatases

Question 13

Receptor Tyrosine Kinases

Answer 13

a. Dimerize and autophosphorylate when ligand binds
b. FALSE Are used by epinephrine and glucagon
c.
Activate target proteins that may influence cell growth and division
d. FALSE Initiate the transduction leading to fat mobilization

Question 14

Acetylcholine is a neurotransmitter that

Answer 14

a.
signals a post-synaptic cell by binding to a site on an acetycholine-gated ion channel
embedded in the plasma membrane
b. FALSE triggers Na+ to rush out of the cytoplasm against its concentration gradient
c.
causes a change in voltage measured across the membrane of the post-synaptic cell
d. FALSE excites a post-synaptic neuron by entering its cytoplasm

Question 15

Epidermal Growth Factor (EGF) and Nerve Growth Factor (NGF)

Answer 15

Upon ligand bonding, the recepter dimerizes and phosphorylates itself. Is a type of RTK

Question 16

Insulin

Answer 16

Function is to let glucose in after a meal. Receptor type is RTK. It phosphorylates IRSs, which activates a kinase to phosphorylate PIP2 to PIP3, activates PKB. PKB activates Akt. Signalling is terminated by protein phosphatases to remove phosphates from activated proteins in insulin signal transduction pathway

Question 17

Nuclear Receptor

Answer 17

Transcription factors that contain a hormone binding domain and DNA binding domain. Upon binding to hormone, will go into the nucleus and recognize a specific nucleotide sequence.

Question 18

G protein

Answer 18

Trimeric protein. Conformational change from the binding of the ligand (e.g. epinephrine) causes a molecule of GDP to unbind and GTP to bind. Causes subunits to disassociate and protein is now activated and activates adenylyl cyclase

Question 19

Proto-oncogenes

Answer 19

Often RTK genes because they can be converted to an oncogene.

Question 20

Adenylyl cyclase

Answer 20

A membrane-bound protein that catalyzes the reaction.
H20+ATP->cAMP
The one phosphate that is left, is binding at 1’ and 3’

Question 21

G protein α subunit

Answer 21

Upon activation, exchanges a GDP for a GTP and disassociates from By dimer and moves in membrane-plane to activate adenylyl cyclase. Also functions as a GTPase that cleaves bound GTP to GDP, causing it to spontaneously reassociate with By dimer and deactivating G protein

Question 22

IP3 (Inositol triphosphate)

Answer 22

Comes from cleavage of phsophotidylinositol by phospholipase C. May bind to calcium channels in ER, sending calcium into the cytoplasm.

Question 23

Steroids

Answer 23

Binds to Nuclear Hormone receptors

Question 24

Ras (Rous avian sarcoma virus)

Answer 24

Ras is active when bound to GTP and inactive when bound to GDP

Question 25

What binds to steroid hormones?

Answer 25

A nuclear receptor

Question 26

What alters transcription?

Answer 26

Nuclear receptors, and steroids

Question 27

What opens Ca++ channels?

Answer 27

IP3 (inostisol triphosphate)

Question 28

What causes GDP to fall out of when ligand binds to it?

Answer 28

Acetylcholine

Question 29

What creates cAMP from ATP?

Answer 29

Adenylyl cyclase

Question 30

What creates GDP from bound GTP?

Answer 30

G protein alpha subunit

Question 31

What dimerizes an RTK?

Answer 31

Epidermal growth factor (EGF) and Nerve Growth Factor (NGF) and Insulin

Question 32

What phosphorylates itself?

Answer 32

RTK (Receptor Tyrosine Kinase)

Question 33

What induces mitosis using Ras?

Answer 33

Epidermal growth factor (EGF) and Nerve Growth Factor (NGF)

Question 34

What is an example of a paracrine factor?

Answer 34

Epidermal growth factor (EGF) and Nerve Growth Factor (NGF)

Question 35

What is an example of a hormone?

Answer 35

Insulin, and steroids

Question 36

What is an example of a neurotransmitter?

Answer 36

Acetylcholine