cell communication Flashcards
1
Q
why is cell signalling needed
A
- maintain homeostasis, controls health
2
Q
stages of the main principles of cell signalling
A
- release of a ligand
- ligand delivery and binding to specific receptor
- receptor activation
- further relay of signal by intracellular response
- activation of target proteins and cellular response
- termination of signal
3
Q
paracrine signalling
A
- signalling to communicate to cells that are nearby
- proteins are cleaved to make them soluble
- when soluble they can move from cells to act on nearby cells
- nerve cells: synaptic signalling, can signal with cells far away
4
Q
endocrine signalling
A
- communicate with cells all over the body through the use of blood vessels
- use of circulatory system
- used by signalling molecules e.g. hormones
5
Q
contact dependent signalling
A
- direct communication with cells in close proximity
- signalling proteins not released but can act on ligand when bound to membrane and bonds with receptor of adjacent cell
6
Q
autocrine signalling
A
- cells express ligand and receptor to self-stimulate
- allows cells to be self-dependent for signals to stimulate their own survival and proliferation
7
Q
how are signalling receptors relayed
A
- g protein coupled receptors
- enzyme coupled receptors
8
Q
how does the g protein coupled receptor work
A
- binding domain > allows conformational change and bonding to G proteins > G protein active enzymes to produce 2nd messenger > 2nd messenger signal
- cells respond to a stimulus to undergo contraction or change shape
9
Q
how do enzyme coupled receptors work
A
- enzymatic domain > conformational change, phosphorylation and activation > activated receptors recruit other adaptor proteins to relay other signalling kinases
10
Q
what are protein kinases
A
- class of enzymes that phosphorylate other proteins
- they differ based on the type of amino acid
- add a phosphate group
11
Q
GTP binding controlling signalling
A
- OFF when GTP proteins are inactivated when GDP is bound
- ON when removal of GDP and binding of GTP activates GTP proteins
- G proteins are GTPases
12
Q
phosphorylation controlling signalling
A
- addition of a phosphate group from ATP to amino acids by protein kinases
- either activate of inactivate a protein
- dephosphorylation by phosphatases removes it
13
Q
what are GPCR’s
A
- largest class of cell-surface signalling receptors
- used for many signals
- ligand binding to a GPCR activates it and allows it to bind to G proteins to further relay the signal
- types: muscarinic receptor, opioid receptor, chemokine receptor
14
Q
what are the 3 types of G proteins
A
- Gs (stimulate adenylyl cyclase)
- Gi (inhibits adenylyl cyclase)
- Gq (activates phospholipase)
15
Q
stages of cell signalling
A
- in resting cell the Gs protein in inactive. alpha subunit is bound to GDP
- when ligand binds to gene proteins - activates the receptor GPCR
- this allows the G protein to bind via alpha subunit
- GPCR activates alpha subunits by displacing GDP for GTP
- active alpha dissociates and binds to adenylyl cyclase to activate it
- adenylyl cyclase makes cAMP using ATP - increases cAMP concentration
- cAMP is second messenger - used to activate protein kinase A
- this activates glycogen phosphorylase which breaks down glycogen to glucose
- increase glucose form Krebs cycle
