Types of receptor
Keywords: receptor, kinetics, effector, transducer, signal, enzyme, ion channel, g-protein, g protein, transcription factor, transmembrane domain, antagonist, partial agonist, inverse agonist, agonist, pharmacodynamics, receptor conformation, active, inactive, down-regulation, up-regulation, law of mass-action
Description: The Worldwide Intensivist
Different people have different ideas about what a receptor is. I rather like the definition of Hucho.
Receptors are proteins interacting with extracellular physiological signals and converting them into intracellular effects
This definition is by no means perfect, but seems far more useful than the blurry definition you find in so many pharmacology textbooks, along the lines of 'a receptor is any functional macromolecular component of an organism to which a drug binds'. We should perhaps avoid semi-religious bickering about the 'essential nature' of receptors, and look at how well the definition works for us!The most important concept is that the receptor:
- Receives a signal; and
- transduces the signal to
- an effector mechanism.
- Receptors as enzymes: These receptors usually span the cell membrane just once, and in response to binding of a ligand, usually increase the phosphorylation of intracellular proteins, for example the tyrosine residues on vital regulatory components (Occasionally, serine or threonine residues are phosphorylated).