lecture 12 - broad principles of cell signaling

Question 1

why is cell signalling important

Answer 1

transfer information
- from environment to cell
- from cell to cell

Question 2

cell signaling effects

Answer 2

metabolism
nervous system
cell cycle
development
immunology
physiology
pharmacology

Question 3

cells respond to

Answer 3

physical and chemical signals

Question 4

methods of cell to cell communication

Answer 4

gap junctions
autocrine and paracrine signals (cells release a signal and can feedback onto that cell or other cells that are local)
hormone
neurotransmitter
neurotransmitter
neurochrome

Question 5

signaling pathways we will learn

Answer 5

1. steroid hormones
2. ligand gated ion channels
3. cyclic AMP pathway
4. phosphoinositide pathway
5. tyrosine kinase pathway

Question 6

chemical signal

Answer 6

e.g. pheromones, hormones, neurotransmitters, cell surface molecules

Question 7

receptor

Answer 7

e.g. ion channel linked, G protein linked, tyrosine kinase linked

Question 8

transducer

Answer 8

e.g. G proteins, non receptor tyrosine kinases

Question 9

amplifier

Answer 9

e.g. adenylyl cyclase, phospholipase C

Question 10

2nd messenger

Answer 10

e.g. cyclic AMP, IP3, Ca2+, DAG, proteins

Question 11

effectors

Answer 11

e.g. protein kinases, Ca2+ binding proteins

Question 12

response element

Answer 12

e.g. enzymes, ion channels, transcription factors

Question 13

response

Answer 13

e.g. metabolism, secretion, contraction, excitability, gene transcription, cell growth

Question 14

amplification

Answer 14

a single hormone receptor interaction can be amplified by up to 10^6

Question 15

heterogeneity - concept of diversity

Answer 15

each pathway component often has multiple forms and cells can mix and match components

Question 16

dynamics

Answer 16

responses are dependent on both temporal and spatial aspects of signaling components

Question 17

amplification example

Answer 17

cAMP signaling pathway:
signal molecule binds to G protein linked receptor which activated the G protein
G protein turns on adenylyl cyclase an amplifier enzyme
adenylyl cyclase converts ATP to cAMP
cAMP activates protein kinase A
protein kinase A phosphorylates other proteins leading to a cellular response

Question 18

information transfer

Answer 18

can be through conformational change
e.g.
chemical signal to receptor, receptor to G protein, G protein to amplifier, 2nd messenger to protein kinase
can be through covalent modification
e.g. phosphorylation
add phosphate from ADP something

Question 19

alpha subunit of G protein is activated when ___ is bound

Answer 19

GTP

Question 20

activated alpha subunit binds to target protein and

Answer 20

activates it

Question 21

hydrolysis of GTP by alpha subunit inactivates the subunit causing it to

Answer 21

dissociate from the target protein

Question 22

inactive alpha subunit re assembles with the beta gamma complex to reform

Answer 22

the G protein ( this is an example of a conformational change having an affect)

Question 23

covalent modification - phosphorylation

Answer 23

addition of phosphate group of ATP to hydroxyl group of amino acid which changes the activity of function of the protein

Question 24

this is reversed by

Answer 24

protein phosphatases