Cell signaling

Question 1

Principle types of detectors of extracellular signaling molecules

Answer 1

1. voltage dependent ion channels
2. ligand dependent ion channels
3. G-protein coupled receptors
4. Enzyme linked receptors
5. nuclear receptors
6. metabolic sensing

Question 2

G-protein coupled receptors

Answer 2

• recognizes ligand and interacts with G-protein

- ie: muscarinic ach receptor

Question 3

Enzyme linked receptors

Answer 3

• enzymatic activity associated with ligand binding

- ie serine/thr kinases

Question 4

nuclear receptors

Answer 4

transcription factors that regulate gene expression

-ie: steroid hormones

Question 5

metabolic sensing

Answer 5

• metabolic changes can cause signal pathways within cells

- ie: glucose induced depolarization of pancreatic beta cells

Question 6

tools of signaling pathway

Answer 6

1. 2nd messengers: molecules that relay signals from a receptor to target molecules in the cell
2. protein modification
   (phosphorylation/acetyl/glycosyl)
3. GTP/GDP

Question 7

Important second messengers

Answer 7

Ca2+ 
DAG
IP3
cAMP
cGMP
NO

Question 8

mechanisms for signal termination

Answer 8

any step in cell signaling cascade can be site for termination

1. extracellular signaling molecules
2. receptors
3. 2nd messengers
4. protein modification
5. protein binding/targeting
6. negative feedback loops
7. phosphodiesterase: dedicated to turn off signals

Question 9

pathway for amplification

Answer 9

amplification: molecule in a cascade activates more than 1 of the next molecule in cascade (> than 1:1)

amplification by positive feedback or signaling cascade

Question 10

Nodes

Answer 10

points in a signaling network that have multiple “input” and “output” molecular pathways

-Ca2+ is most extensive node
a secondary messenger in many pathways.

result: extensive communication between pathways!!

Question 11

Modules

Answer 11

protein complexes that process signals together. works as a unit to transduce a particular signal