Protein Interactions Flashcards
What can proteins form interactions with?
- small ligands
- DNA and RNA
- proteins
- membranes=lipids
- sugars/carbohydrates
What are protein interactions that occur which are sequence specific?
- restriction enzymes
- transcription factors
What are protein interactions which are not sequence specific?
- histone
- helicase
- polymerase
How do proteins interact with other proteins or DNA or lipids?
- usually using non-covalent interactions
- sometimes two proteins can be joined by disulphide bonds
What affects the likelihood and strength of binding of protein interactions?
- availability (conc) and co-localisation
- matching non-covalent interactions
- competition from other partners
What affects the lifetime of the complex and therefore its affect?
- extent of contributing stabilising interactions
- regulators= PH, modification, other ligands
What are some examples of post-translational modification of proteins?
- phosphorylation
- methylation
- ubiquitylation
- acetylation
- SUMOylation
- hydroxylation
How does calmodulin work?
-once it binds to calcium it changes structure in a way that enables it to bind to other partners
What factors make protein interactions more complicated to understand?
- one protein can have many interaction domains
- one protein can interact at the same time with many substrates and ligands
- all of the interactions influence each other and form a complex matrix
What can we measure ligand-protein interaction?
- proteins and ligands have reversible affinity for each other
- they are in equilibrium because always part of them interacts and part does not
- the equilibrium is dynamic and regulated by surroundings, other interactors and modification
What is affinity indicated by?
Kd (disassociation constant)
What is the Kd?
the concentration of substrate/ligand required to achieve half (50%) saturation of protein population
What does a low value of Kd mean?
that the interaction is strong
