Koklič, TilenHrovat, AlenkaGuixà González, Ramon, 1978-Rodríguez Espigares, Ismael, 1990-Navio, DamarisFrangež, RobertUršič, MatjažKubale, ValentinaPlemenitaš, AnaSelent, JanaŠentjurc, MarjetaVrecl, Milka2021-04-122021-04-122021Koklič T, Hrovat A, Guixà-González R, Rodríguez-Espigares I, Navio D, Frangež R, Uršič M, Kubale V, Plemenitaš A, Selent J, Šentjurc M, Vrecl M. Electron paramagnetic resonance gives evidence for the presence of type 1 gonadotropin-releasing hormone receptor (GnRH-R) in subdomains of lipid rafts. Molecules. 2021; 26(4):973. DOI: 10.3390/molecules260409731420-3049http://hdl.handle.net/10230/47084This study investigated the effect of type 1 gonadotropin releasing hormone receptor (GnRH-R) localization within lipid rafts on the properties of plasma membrane (PM) nanodomain structure. Confocal microscopy revealed colocalization of PM-localized GnRH-R with GM1-enriched raft-like PM subdomains. Electron paramagnetic resonance spectroscopy (EPR) of a membrane-partitioned spin probe was then used to study PM fluidity of immortalized pituitary gonadotrope cell line αT3-1 and HEK-293 cells stably expressing GnRH-R and compared it with their corresponding controls (αT4 and HEK-293 cells). Computer-assisted interpretation of EPR spectra revealed three modes of spin probe movement reflecting the properties of three types of PM nanodomains. Domains with an intermediate order parameter (domain 2) were the most affected by the presence of the GnRH-Rs, which increased PM ordering (order parameter (S)) and rotational mobility of PM lipids (decreased rotational correlation time (τc)). Depletion of cholesterol by methyl-β-cyclodextrin (methyl-β-CD) inhibited agonist-induced GnRH-R internalization and intracellular Ca2+ activity and resulted in an overall reduction in PM order; an observation further supported by molecular dynamics (MD) simulations of model membrane systems. This study provides evidence that GnRH-R PM localization may be related to a subdomain of lipid rafts that has lower PM ordering, suggesting lateral heterogeneity within lipid raft domains.application/pdfeng© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).info:eu-repo/semantics/articlehttp://dx.doi.org/10.3390/molecules260409737TM receptorsElectron paramagnetic resonance (EPR)Lipid raftsPlasma membraneType 1 gonadotropin-releasing hormone receptorinfo:eu-repo/semantics/openAccess