Cellular Receptors of Relevance to Therapeutics

This table provides a summary of the various types of cellular receptors that are drug targets.

Classes	Subclasses or families	Physiological ligands	Transducers, principal effects, or ions
G protein-coupled receptors (GPCRs)^a	Adhesion Frizzled Glutamate Rhodopsin Secretin	Very large number of endocrine and paracrine factors, but other types of ligands as well	G proteins G_s: Adenylyl cyclases (stimulation) G_i: Adenylyl cyclases (inhibition), delayed rectifier K⁺ channel (stimulation), N-type voltage-gated Ca²⁺ channel (inhibition) G_q: Phospholipase C-β (stimulation)
Ligand-gated ion channels^b	Glutaminergic Nicotinic cholinergic P2X 5-HT₃ TRP GABA_A Glycine	Glutamate ACh ATP 5-HT₃ Many ligands GABA Glycine	Na⁺ and K⁺ principally, but Ca²⁺ as well in certain circumstances Na⁺, K⁺, Ca²⁺ Na⁺, K⁺, Ca²⁺ Na⁺, K⁺, Ca²⁺ Na⁺, Ca²⁺, Mg²⁺ Cl⁻ Cl⁻
Enzyme-linked (catalytic) receptors	Receptor tyrosine kinases Receptor serine kinases Membrane bound GC	Insulin, PDGF, EGF, VEGF, growth factors^d TGF-β family Natriuretic peptides	Proteins containing SH2 and PTB domains SMADs Cyclic GMP
Other cell-surface membrane receptors	Cytokine receptors Toll-like receptors TNFα receptors	Interleukins and other cytokines, growth hormone, prolactin PAMPs TNFα	JAK/STATs, soluble tyrosine kinases TIRAP, TRAM TRADD, RIP-1, TRAF2
Nuclear receptors^c	Steroid receptors (subfamily 3) Nonsteroid receptors (subfamilies 1, 2, 4–6)	Corticosteroids, sex hormones Thyroxine, retinoic acid, hydroxycholesterols, bile acids, Vitamin D	Coactivators Coactivators, corepressors

SMAD, a concatenation of SMA (small worm phenotype in C. elegans) and MAD (Mothers Against Decapentaplegic in Drosophila); TIRAP, toll-interleukin 1 receptor domain-containing adaptor protein; TRADD, TNF receptor–associated death domain; TRAF2, TNF receptor–associated factor 2; TRAM, TRIF-related adapter molecule, wherein TRIF represents TIR domain-containing adapter-inducing interferon-β and TIR is toll-interleukin 1 receptor.

^aThe GPCR families are listed according to the GRAFS system (Fredriksson et al., 2003), which is based on phylogenetic analyses of the human genome; other systems of classification exist. It is important to note that each family of GPCRs contains a large number of receptors that respond to agonists and communicate with transducers distinct from the family’s namesake. See Figure 3–14 and legend.

^bGlutaminergic receptors comprise the AMPA, kainate, and NMDA receptors. Many permutations of each of these subtypes and of other subclasses of ligand-gated ion channels exist owing to combinatorial diversity in subunit composition. Ion channels that are gated by internal ligands are not listed for the purposes of brevity but are discussed in the text.

^cNuclear receptors are generally grouped into six subfamilies. The table groups the subfamilies into two major classes, steroid receptors and nonsteroid receptors, as does the IUPHAR/BPS Guide to Pharmacology.

^dThe list comprises only a selection from among many different agonists.

Source

Adapted from: Manning DR, Blumenthal DK. Pharmacodynamics: Molecular Mechanisms of Drug Action. In: Brunton LL, Knollmann BC. eds. Goodman & Gilman's: The Pharmacological Basis of Therapeutics, 14th Edition. McGraw-Hill Education; 2023. Accessed January 14, 2025.