Protein activation/inhibition, receptors, signal transduction Flashcards
What are the 4 common steps to producing a cellular response?
- chemical substance travels from source
- binds to target protein
- causes activation or inhibition
- change to cellular response
Name differences between enzymes and receptors (3)
• enzymes have 1 active site while receptors can have multiple binding sites
• enzymes bind ‘substrates’, while receptors bind ‘ligands’
• enzymes change substrate into product, while receptors release ligand unchanged
What is the same about enzymes and receptors?
• can be either membrane bound or free in the cytosol
• can be activated or inhibited
What property ensures that the right ligand binds to open the receptor?
specificity
What is an agonist?
A chemical substance which binds to a receptor and ACTIVATES it.
What happens to the receptor when the ligand binds
undergoes a conformational change in order to be become activated
What is an antagonist?
A chemical substance which binds to a receptor and PREVENTS ACTIVATION by an agonist.
Does the receptor undergo a conformational change when an antagonist binds?
No, because it is not activated
What is a second messenger?
Relay molecules used in signal transduction to transmit signal from receptor to other relay molecules, free to move in cell (i.e. not membrane bound)
What do GPCR use to start signal transduction?
G proteins, which then communicate to other proteins in the cell
What do RTKs use to start signal transduction?
phosphorylation of adaptor proteins
What is a widespread mechanism for regulating protein activity?
Phosphorylation and dephosphorylation
What is phosphorylation?
when protein kinases transfer phosphates from ATP to protein
What are the 3 types of receptor that we study?
GPCRs, RTKs, ligand-gated ion channels
How do ligand-gated ion channels work?
an agonist bind which causes an conformational change to activate/open the receptor and allow ions to flow