Cell Signalling Flashcards
How does a signal get to a response
Signal
Receptor
Transducers eg sm
Effectors which cause response
Response
What can transducers do
Amplify signal from receptor
Give example of effectors
Tf, metabolism enzymes eg glycogen synthase, cytokine
What is cross talk
Overlap in signals where 2 receptor signals can have same transducer eg same sm camp but cause diff responses
How does transducer determine which signal should work in cross talk
Affinity of binding affects it (if bound more then this signal is transduced) and different trigger levels eg diff levels of phosphorylation
What are the 3 types of signal
Endocrine for long distance in BV
Paracrine
Autocrine
Give example of paracrine signalling
Tgf b release
What type of molecules use cell surface receptors
Hydrophilic eg Nt, cytokines, adrenaline
What binds ic
Hydrophobic eg steroid oestrogen hormone, NO
What are the 3 cell surface receptors
Ion channels (ionotropic) (ligand, voltage, mech)
Gpcr (metabotropic)
Enzyme linked receptors eg rtk
Which cell surface receptor is quickest showing signals have different speeds of onset
Ion channels (milliseconds)
Which is the slowest cell surface receptors
Enzyme linked
What 2 effects do gpcr have
Affect permeability of ion channels eg ca
Or
Regulate enzyme activity which produce secondary messengers eg adenylyl cyclase
which gpcr subunit holds and exchanges gtp for activation
A
Dissociates from b and y
How many passes do gpcr have in transmembrane vs enzyme linked
7 vs 1
What is the ic catalytic domain in rtk
Tyrosine kinase domain
What would binding to rtk cause
Dimerisation (unless igf insulin receptor which is already a dimer) and autophosphorylstion
What are gpcr usually called
Serpentine
Is the n terminal of gpcr ic or EC
EC and c domain is ic
Which 2 enzymes are phos and regulated by gpcr a subunit
Phospholipase c (ip3 and dag production ) and adenylyl cyclase (camp production )
Give example of pka activity activated by camp eg when glucagon binds
Phosphorylation of glycogen phosphorylase kinase
Which activates phosphorylase a
(Blocks glycogen synthase)
What does dag activate
Pkc
What does secondary messenger cgmp do
Activates pk g eg for smooth muscle relaxation
Give example of a rtk which needs dimerised
Egf receptor
What allows specific protein binding and phos on the tyrosine kinase residues
The aa sequence flanking the tyrosine residue binding site
Which gpcr needs extra fast activation and slow deactivation
Rhodopsin for light change
Which gpcr needs slow activation
B2
How is amplification usually by
Increase in secondary messengers
What is the exception to amp
Rhodopsin which reduces cgmp
