General principles II Flashcards
Why is achieving specificity in signalling challenging
The cytosol is a noisy and crowded environment
How can specificity be achieved?
Signalling complexes
Name 3 different signalling complexes
- Preformed signalling complex on scaffold protein; 2. Assembly of signalling complex on activated receptor; 3. Assembly of signalling complex on phosphoinositide docking sites
What is a scaffold protein
Physical link that orients players in a particular pathway
What does the modular architecture of domains allow
Cooperative binding - increases affinity and specifity
What favours rapid rebinding
High density of binding sites
How does membrane association make molecular interactions efficient
Tethers protein to the membrane. Reduces number of unproductive encounters. Degrees of freedom reduced.
What is the speed and persistence range of signal responses
Milliseconds to days
Examples of transient responses
Fast turnover of signal, negative feedback loops, adaptation (& oscillations)
Examples of long-lasting (permanent response)
Positive feedback loops, switch-like behaviour
Examples of adaptation mechanisms
Receptor sequestration, receptor down-regulation, receptor inactivation, signalling protein inactivation, production of inhibitory protein
Logic gates
AND: both, NOR: neither, OR: both or either, XOR: only one
What generates complex response behaviour
Combination of feedback loops with logic gates
