9. Cell Signalling Overview Flashcards
name 3 hydrophobic signals
steroids
retinoids
thyroxine
what is the most common method of signalling
extracellular mediator signals
what is autocrine signalling
signalling and reception by the same cell
when does autocrine signalling frequently occur
cell division
- growth regulation
what is paracrine signalling?
signalling between nearby cells
what is endocrine signalling
signalling via distant cells via hormones
describe the effects of paracrine signalling
local and short lived
when may paracrine signalling be used
in embryonic development
what type of signalling is synaptic signalling
paracrine signalling - between two nerve cells or at a neuromuscular junction
what does endo mean?
within
what type of glands are involved in endocrine signalling
ductless glands that secrete hormones
give an example of an endocrine gland
pituitary
adrenal
thyroid
name 3 types of extracellular mediators
hormones
growth factors
steroid hormone
name 3 types of receptors
G-protein coupled receptors
receptor tyrosine kinases
ion channel receptors
how many TMS Alpha helices in GPCRs
7
how many extracellular and intracellular domains in GPCRs
4 extracellular & 4 cytosolic
name 3 processes GPCRs are involved in
metabolism
movement
modulating gene expression
GPCRs work with the help of a G-protein- what can this bind
what does this act as
can bind guanine nucleotides:
GTP & GDP
acts as a molecular switch
what happens when GDP is bound?
G-protein is inactive
SWITCHED OFF
What happens when GTP is bound
G-protein is activated
SWITCHED ON
what side of the membrane is the G-protein attached to loosely
cytoplasmic side of the cell membrane
how do receptor tyrosine kinases (RTKs) differ to GPCRs
RTKs have intrinsic enzyme activity
what happens when a ligand binds to a RTK
previously exist as monomers
when activated- dimerisation occurs = activating a kinase
define second messengers
intracellular metabolite or ion which couples an extracellular stimulus to a physiological response
name 4 criteria a molecule must fulfil to be classed a second messenger:
- be small
- can be rapidly produced & hydrolysed
- controlled by extracellular stimuli
- able to be amplified
give 2 examples of cyclic nucleotide second messengers
cAMP
cGMP
give 2 examples of lipid-derived second messengers
1,2 diacylglycerol
Inositol 1,4,5 triphosphate
what does cAMP activate
protein kinase A
what does cGMP activate
protein kinase G
what does IP3 activate
calcium dependent protein kinases
what is cAMP used for
increase lipid hydrolysis
decrease glycogen synthesis
what is cGMP used for
opens cation channels in rod cells
what does IP3 do
opens calcium channels in the ER
what does DAG activate
protein kinase C
is phosphorylation reversible or irreversible?
reversible
what molecule is involved in dephosphorylation
protein phosphatase
