title: Photoaffinity labeling of the sigma-1 receptor with N-[3-(4-nitrophenyl)propyl]-N-dodecylamine: evidence of receptor dimers.
abstract: The sigma-1 receptor is a ligand-regulated endoplasmic reticulum (ER) resident chaperone involved in the maintenance of cellular homeostasis. Coupling of the sigma-1 receptor with various ER and/or plasma membrane ion channels is associated with its ability to regulate the locomotor activity and cellular proliferation produced in response to sigma-1 receptor ligands. A number of endogenous small molecules bind to the sigma-1 receptor and have been shown to regulate its activity; these include progesterone, N,N-dimethyltryptamine, d-erythro-sphingosine, and/or other endogenous lipids. We previously reported the synthesis of long chain N-alkylamine derivatives and the characterization of the structure-activity relationship between the chain length of N-alkylamine and affinities at the sigma-1 receptor. Here, we present data demonstrating the photoincorporation of one of these N-alkylamine derivatives, N-[3-(4-nitrophenyl)propyl]-N-dodecylamine (4-NPPC12), to the sigma-1 receptor. Matrix-assisted laser desorption ionization time-of-flight and tandem mass spectrometry showed that 4-NPPC12 photoinserted at histidine 154 of the derivatized population of the sigma-1 receptor. Interestingly, light-dependent photoinsertion of 4-NPPC12 resulted in an enhanced electrophoretic mobility of only 50% of the derivatized receptor molecules as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The proposed binding and reactivity of 4-NPPC12 evoke a ligand binding model for the sigma-1 receptor that likely involves a receptor dimer and/or oligomer.
authors: Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States.
authors: Uyen B
authors: UB
authors: Chu
authors: Subramaniam
authors: S
authors: Ramachandran
authors: Abdol R
authors: AR
authors: Hajipour
authors: Arnold E
authors: AE
authors: Ruoho
mesh_terms: D000345:Affinity Labels / Q000737:chemistry*; D000588:Amines / Q000737:chemistry*; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002522:Chlorocebus aethiops; D015870:Gene Expression; D006168:Guinea Pigs; D008027:Light; D055668:Photochemical Processes; D055503:Protein Multimerization; D051381:Rats; D017480:Receptors, sigma / Q000032:analysis* / Q000235:genetics; D000097605:Sigma-1 Receptor
chemical_list: D000345:Affinity Labels; D000588:Amines; D017480:Receptors, sigma; D000097605:Sigma-1 Receptor; C003935:dodecylamine