Traditional pharmacology posits that a ligand can be either classified as an agonist (full or partial), antagonist or more recently an inverse agonist through a specific receptor subtype, and that this characteristic will be consistent with all effector (second messenger) systems coupled to that receptor. While this dogma has been the backbone of ligand-receptor interactions for decades now, more recent data indicates that this classic definition of ligand-protein associations does not hold true for a number of compounds.
Functional selectivity posits that a ligand may inherently produce a mix of the classic characteristics through a single receptor isoform depending on the effector pathway coupled to that receptor. For instance, a ligand can not easily be classified as an agonist or antagonist, because it can be a little of both, depending on its preferred signal transduction pathways. Thus, such ligands must instead be classified on the basis of their individual effects in the cell, instead of being either an agonist or antagonist to a receptor.
It is also important to note that these observations were made in a number of different expression systems and therefore functional selectivity is not just an epiphenomenon of one particular expression system.
Functional selectivity of G protein-coupled receptor ligands; new opportunities for drug discovery.(Brief article)(Book review)
Sep 01, 2009; 9781603273343 Functional selectivity of G protein-coupled receptor ligands; new opportunities for drug discovery Ed. by Kim...
New drug discovery and development data have been reported by scientists at Penn State University, Department of Pharmacology.
Nov 10, 2010; Data detailed in 'Third generation antipsychotic drugs: partial agonism or receptor functional selectivity' have been presented....