GPCR's and G Proteins



- Refers to the common mode of receptor signalling via GTP-binding proteins on the inside of cells 

-They mediate a range of outside signals and convay these signals to the inside of the cell and elicit a series of reactions which eventually deliver a message and an appropriate cellular and physiological response

Receptor signalling relies on allosteric coupling: 

-Binding of agonist increases the affinity for the G-protein on the inside of the cell 

-The binding of G-protein increases the receptors affinity for agonist binding to the same extent

Signalling mechanism:

-Ligand doesn't pass through the membrane

-Instead, signal is transferred to the inside of the cell by conformational changes in the receptor protein which is coupled to ligand binding events

-An increase in the concentration of agonist outside of the cell results in an increase in the number of receptors bound to the ligand 

G Proteins: 

-Specialised proteins with the ability to bind the nucelotides GTP and GDP 

-G proteins that associate with GPCR's are Heterotrimeric; 


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