VPT 311: General and Systemic Veterinary Pharmacology (2+1)

TYPES OF RECEPTORS

• Type I – Channel linked receptors (ligand-gated ion channels or inotropic receptor) – These are also known as ionotropic receptors. These are membrane receptors that are coupled directly to ion channels and are the receptors on which fast neurotransmitters act. Examples include nicotinic acetylcholine receptors and glutamate receptors.
• Type II – G-Protein coupled receptors (metabotropic receptors) – These are also known as metabotropic receptors or 7-transmembrane spanning receptors. They are membrane receptors that are coupled to intracellular effector systems via a G-protein. This class includes receptors for many hormones and slow transmitters. Examples include muscarinic acetylcholine receptors and adrenergic receptors.
• Type III – Kinase-linked receptors – These are membrane receptors that incorporate an intracellular protein kinase domain within their structure. They include receptors for insulin, various cytokines and growth factors. Closely related are receptors linked to guanylate cyclase such as the atrial natriuretic factor receptor.
• Type IV – Receptors that regulate gene transcription (nuclear recptors) – These are also known as nuclear receptors, though some are actually located in the cytosol rather than the nuclear compartment. They include receptors for steroid hormones and thyroid hormone.