TABLE 1

Selected examples of putative endogenous GPCR allosteric modulators

ModulatorTargets
Ions
 Na+Various
 Zn2+Various
 Mg2+μ-OR, κ-OR, β1-AR
 Mn2+μ-OR, δ-OR, κ-OR, β-AR
Amino acids and derivatives
l-Phe/l-Trp/l-TyrCaSR
l-Leu/l-Ile/l-PheGABABR
 HomocysteineD2R
 Agmatineα2D-AR
Peptides
 Melanotrophin release inhibiting factor 1D2R
 5-HT–moduline5-HT1B/1D
 GlutathioneCaSR
Larger peptides/proteins
 Pepcan-12CB1R
 Dynorphin-AM2 mAChR
 ProtamineM2 mAChR
 Myelin basic proteinM2 mAChR
 Major basic proteinM2 mAChR
Lipids
 Oleamide5-HT2C/2AR(s), 5-HT1AR, 5-HT7R
 AnandamideM1/4 mAChR(s), M1 mAChR, hA3R
 2-AGhA3R
 Arachidonic acidmAChR(s)
 Lipoxin A4CB1R
 Progesterone (P4)rOTR
 5β-DihydroprogesteronehOTR
 CholesterolRhodopsin, β2-AR, OTR, A2AR, 5-HT1A
 PregnenoloneCB1R
Autoantibodies
 IgG5-HT4R, α1-AR, AT1R, β1-AR, β2-AR, CaSR, D2R, ETAR, GABABR, M1 mAChR, M2 mAChR, M3 mAChR, mGluR1, mGluR5, TSH-R
  • A2AR, adenosine A2a receptor; AT1R, angiotensin II receptor type 1; CB1R, cannabinoid receptor type 1; D2R, dopamine receptor D2; ETAR, endothelin receptor type A; hA3R, human adenosine A3 receptor; hOTR, human oxytocin receptor; 5-HT1AR, serotonin 5HT1a receptor; 5-HT2C/2AR(s), serotonin 5-HT2c/2a receptors; 5-HT7R, serotonin 5-HT7 receptor; OTR, oxytocin receptor; rOTR, rat oxytocin receptor; TSH-R, thyrotropin receptor.