Cell Signalling (Overview)

Question 1

Hydrophobic signals

Answer 1

diffuse through PM and bind to cytosolic receptors

e. g. steroids, retinoids, thyroxine
1. signal
2. perception
3. response

Question 2

Extracellular mediator

Answer 2

binds to cell-surface receptor

1. signal
2. perception
3. transduction
4. response

Question 3

How does transduction in extracellular mediators work?

Answer 3

~ enzyme activation
~ enzyme cascade
~ second messenger
~ protein translocation
~ activation of TF

Question 4

Endocrine signalling

Answer 4

~ long range
~ blood borne hormones
~ secretion of hormone by gland into blood

Question 5

Paracrine

Answer 5

~ short range
~ localised action growth factors + cytokines
~ adjacent target cell
~ use paracrine activating factors

Question 6

Autocrine

Answer 6

~ same cell

~ growth factors + cytokines

Question 7

Name the three types of extracellular mediators

Answer 7

~ hormones
~ growth factors
~ steroid hormones

Question 8

Hormones

Answer 8

~ endocrine
~ blood borne
~ short term metabolic effects - typically ‘washed away’

Question 9

Growth factors

Answer 9

~ paracrine or autocrine

~ generally long term proliferation/developmental effects

Question 10

Steroid hormones

Answer 10

~ intracellular repceptors

~ long term effects

Question 11

Name six receptors involved in cell signalling.

Answer 11

~ receptor-associated kinase
~ GPCRs
~ protein subunit dissociation
~ protein cleavage
~ intrinsic kinase activity
~ ion channels

Question 12

GPCR

Answer 12

~ G-protein coupled receptors
~ contains a transmembrane alpha helix
~ short-term changes in cell function e.g. metabolism or movement

Question 13

Receptors with intrinsic kinase activity

Answer 13

~ intrinsic kinase activity
~ receptor serine kinases
~ receptor tyrosine kinases

Question 14

Receptor serine kinases

Answer 14

e.g. TGF-beta receptors - phosphorylate and activate Smad transcription factors

Question 15

Receptor tyrosine kinases

Answer 15

e.g.
platelet derived growth factor receptor
insulin receptor
epidermal growth factor receptor
~ dimers when active
~ monomers when inactive

Question 16

Receptor-associated kinase

Answer 16

long term changes in gene expression or development

Question 17

Ion channel receptors

Answer 17

bind to ligand and the channel function changes

e.g. nicotinic acetylcholine receptor (Na+ channel)

Question 18

Second messenger

Answer 18

intracellular ion/metabolite which couples an extracellular stimulus to a physiological response