Targets for Drug Action: Overview

Typically, drugs target specific macromolecules such as receptors, ion channels, transporters, or enzymes.

Many drugs bind receptors. Receptors are either cell surface molecules, intracellular proteins in the cytosol, or proteins associated with organellar membranes. Upon receptor binding, agonist drugs induce the same molecular reactions as endogenous ligands, activating effector proteins and eliciting a cellular response.

On the other hand, antagonists block receptor activity and inhibit the cellular response.

Some drugs target ion channels and disturb ion movement. They may bind at ligand-binding sites or allosteric sites or block the channel's pores to regulate the opening and closing of the channel.

The altered ion flow changes the cell membrane potential, impacting cellular activities such as muscle contraction or neurotransmission.

Other drugs target transporters and block the movement of metabolites or ions across the cell membrane.

Finally, drugs can mimic native substrates to bind to the target enzyme. Such interactions can inactivate the enzyme or yield abnormal products, disrupting cellular pathways.