The fungal protein ERG2, a C-8 sterol isomerase, falls into the sameprotein family as sigma-1. Both localize to theER membrane, although sigma-1 is also reported to be a cell surface receptor. Sigma-2 is an EXPERA domain protein[4] with a mostly intracellular (ER membrane) localization.[5]
Because the σ-receptor was originally discovered to be agonized bybenzomorphanopioids and antagonized bynaltrexone, σ-receptors were originally believed to be a type of opioid receptor.[6] When the σ1 receptor was isolated and cloned, it was found to have no structural similarity to the opioid receptors, but rather showed similarity to fungal proteins involved in sterol synthesis.[7] At this point, they were designated as a separate class of proteins.
The abundant neurosteroid steroid hormoneDHEA is an agonist at sigma receptors and along withpregnenolone could be endogenous agonist ligands; opposed by sigma antagonistic activity fromprogesterone.[9] Another endogenous ligand,N,N-dimethyltryptamine, was also found to interact with σ1.[10][11]
^Skuza G, Rogóz Z (June 2006). "The synergistic effect of selective sigma receptor agonists and uncompetitive NMDA receptor antagonists in the forced swim test in rats".Journal of Physiology and Pharmacology.57 (2):217–29.PMID16845227.
^Kim FJ, Pasternak GW (2017). "Introduction to Sigma Proteins: Evolution of the Concept of Sigma Receptors".Sigma Proteins: Evolution of the Concept of Sigma Receptors. Handbook of Experimental Pharmacology. Vol. 244. Cham: Springer International Publishing. pp. 1–11.doi:10.1007/164_2017_41.ISBN978-3-319-65853-7.PMID28871306.
^Vollenweider FX, Leenders KL, Oye I, Hell D, Angst J (February 1997). "Differential psychopathology and patterns of cerebral glucose utilisation produced by (S)- and (R)-ketamine in healthy volunteers using positron emission tomography (PET)".European Neuropsychopharmacology.7 (1):25–38.doi:10.1016/S0924-977X(96)00042-9.PMID9088882.S2CID26861697.
^Klepstad P, Maurset A, Moberg ER, Oye I (October 1990). "Evidence of a role for NMDA receptors in pain perception".European Journal of Pharmacology.187 (3):513–8.doi:10.1016/0014-2999(90)90379-k.PMID1963598.
^Calabrese JR,Suppes T, Bowden CL, Sachs GS, Swann AC, McElroy SL, Kusumakar V, Ascher JA, Earl NL, Greene PL, Monaghan ET (November 2000). "A double-blind, placebo-controlled, prophylaxis study of lamotrigine in rapid-cycling bipolar disorder. Lamictal 614 Study Group".The Journal of Clinical Psychiatry.61 (11):841–50.doi:10.4088/jcp.v61n1106.PMID11105737.S2CID71423264.
^Peeters M, Romieu P, Maurice T, Su TP, Maloteaux JM, Hermans E (April 2004). "Involvement of the sigma 1 receptor in the modulation of dopaminergic transmission by amantadine".The European Journal of Neuroscience.19 (8):2212–20.doi:10.1111/j.0953-816X.2004.03297.x.PMID15090047.S2CID19479968.
^Kamei J (Oct–Dec 1996). "Role of opioidergic and serotonergic mechanisms in cough and antitussives".Pulmonary Pharmacology.9 (5–6):349–56.doi:10.1006/pulp.1996.0046.PMID9232674.
^Krutetskaya ZI, Melnitskaya AV, Antonov VG, Nozdrachev AD (May 2019). "Sigma-1 Receptor Antagonists Haloperidol and Chlorpromazine Modulate the Effect of Glutoxim on Na+ Transport in Frog Skin".Doklady. Biochemistry and Biophysics.484 (1):63–65.doi:10.1134/S1607672919010186.PMID31012016.S2CID126409347.
^Matsumoto RR, Gilmore DL, Pouw B, Bowen WD, Williams W, Kausar A, Coop A (May 2004). "Novel analogs of the sigma receptor ligand BD1008 attenuate cocaine-induced toxicity in mice".Eur J Pharmacol.492 (1):21–6.doi:10.1016/j.ejphar.2004.03.037.PMID15145701.
^Daniels A, Ayala E, Chen W, Coop A, Matsumoto RR (August 2006). "N-[2-(m-methoxyphenyl)ethyl]-N-ethyl-2-(1-pyrrolidinyl)ethylamine (UMB 116) is a novel antagonist for cocaine-induced effects".Eur J Pharmacol.542 (1–3):61–8.doi:10.1016/j.ejphar.2006.03.062.PMID16797004.
^Tapia MA, Sage AS, Fullerton EI, Judd JM, Hildebrant PC, Will MJ, Lever SZ, Lever JR, Miller DK (March 2020). "The sigma receptor ligand N-phenylpropyl-N'-(4-methoxyphenethyl)3piperazine (YZ-067) enhances the cocaine conditioned-rewarding properties while inhibiting the development of sensitization of cocaine in mice".Psychopharmacology (Berl).237 (3):723–734.doi:10.1007/s00213-019-05411-z.PMID31822924.
^Matsumoto RR, Potelleret FH, Mack A, Pouw B, Zhang Y, Bowen WD (April 2004). "Structure-activity comparison of YZ-069, a novel sigma ligand, and four analogs in receptor binding and behavioral studies".Pharmacol Biochem Behav.77 (4):775–81.doi:10.1016/j.pbb.2004.01.014.PMID15099923.