Receptor And Signaling Supplement (3)

Question 1

What is endocrine signaling

Answer 1

Signal (hormone) transported via blood
Long distance and short acting
Freely diffusing signals

Question 2

Paracrine signaling

Answer 2

Signal (paracrine factor) diffuses to neighboring target cell of a different cell type

Local short lived signaling

Question 3

Autocrine signaling

Answer 3

Secreting cells express surface receptors for the signal

Ex. Is growth factor in cancer cells

Question 4

Direct/juxtacrine signaling

Answer 4

Signal binds to signaling cell which then binds to receptor on the target cell

Question 5

How long is short-term signaling

Answer 5

Seconds to minutes

Question 6

How long is long-term signaling

Answer 6

Hours to days

Question 7

Can hydrophilic signals penetrate the plasma membrane?

Answer 7

No

Question 8

Examples of hydrophilic signaling

Answer 8

Epinephrine, insulin, glucagon

Question 9

How do hydrophilic signals work

Answer 9

Signal binds with specific cell membrane receptor

Initiates production of secondary messenger within cell (generally small and derived from AA)

Question 10

What two receptors are involved in hydrophilic signaling

Answer 10

G proteins

RTKs

Question 11

How does lipophilic signaling work

Answer 11

Lipophilic signals pass through plasma membrane and bind to specific receptor proteins within cell

Molecule-receptor complex acts as a transcription factor

Typically have long half-lives

Question 12

Cytoplasmic recpetors

Answer 12

Is a DNA binding transcription factor
Exists in an inactive state with HSP 90
Upon binding to ligand, HSP dissociates

Question 13

How many subunits are in a trimeric G protein

Answer 13

3

Aby

Question 14

To become active, what does GPCR have to do

Answer 14

It must exchange its GDP for GTP

This occurs via the action of guanine exchange factor (GEF)

Question 15

How does GPCR return to inactive state?

Answer 15

G protein hydrolyzes GTP back to GDP using GTPase-activating protein (GAP)

Question 16

How do toxins fuck up the CFTR

Answer 16

Toxins activate adenyly cylcase which makes cAMP from ATP

Excess ATP opens CFTR and then they whole water thing begins

Question 17

Beta-adrenergic receptor

Answer 17

Is a Gs GPCR (stimulates adenylate cyclase)

Causes:
Relaxation of bronchial and intestinal smooth muscle
Contraction of heart muscle
Glycolysis in muscle

Question 18

Histamine H2 recpetor

Answer 18

Is a Gs GPCR

Causes allergic reaction and release of histamines

Question 19

Alpha-adrenergic receptor

Answer 19

Is a Gi GPCR

Causes constriction of smooth muscle

Question 20

Dopamine D2 Receptor

Answer 20

Is a Gi GPCR

Causes increased HR

Question 21

Muscarinic acetylcholine M2 receptor

Answer 21

Is a Gq GPCR receptor

Causes brochoconstriction and stimulation of salivary glands

Question 22

What are the different ways to desensitize a mechanisim

Answer 22

1. Drop hormone levels - decreased adenylyl cyclase activity leads to decrease cAMP and decreased PKA activity
2. Remove the signaling hormone - phosphodiesterase will remove cAMP
3. Receptor sequestration with an endosome
4. Receptor destruction with an endosome and a lysosome

Question 23

Three parts of RTK

Answer 23

ECD - contains signaling molecule binding site
Single Helix that spans the membrane
ICD - possesses tyrosine kinase activity

Question 24

Steps in RTK signaling

Answer 24

1. Binding of ligand to ECD causes dimerization which phosphorylates the tryosine residue
2. Phospho-tyrosines are recognized by adapter and two docking proteins (SH2) and docking protein targets in cytoplasm through RAS-dependent (MAPK)
3. Triggers phosphorylation of protein targets in the nucleus, plasma membrane, and cytoplasm. This leads to alteration in gene transcription and protein activity
4. Signal terminated by degradation of ligand

Question 25

RAS independent pathways uses what type of molecule in signaling?

Answer 25

Another type of kinase