Erhan Yarar, Aytug Altundag, Christopher E Mason, Michael Aschner, Emirhan Harbi
The Endoterpenoid System (ETS) is a proposed new membrane-based framework that ensembles classical endocannabinoid signaling (ECS) with ectopically expressed olfactory GPCRs, ion channels, and microbially derived terpenoids. Integrated with this model is the proposed endoterpenoidome (eTBome) machine: a chemically diverse pool of endogenous cannabinoids, dietary terpenoids, and microbial metabolites whose lipophilicity drives partitioning into cholesterol-rich lipid rafts. Within these nanoscale microdomains, ETS components undergo co-localization and co-expression, enabling receptor heteromerization and β-arrestin-scaffolded signalosomes that facilitate dynamic crosstalk and emergent responses such as bistable apoptotic switches and context specific modulation of Gᵢ/o, Gₛ/olf, and Gq pathways. We detail molecular mechanisms underpinning ETS behavior, including lipid mediated allostery, scaffold protein recruitment, and lateral diffusion effects, and highlight the gut microbiota as pivotal architects of the eTBome through terpene synthase-driven production of bioactive ligands. Germ free and antibiotic treated animal models underscore the dependence of ETS ligand pools and receptor distributions on microbial colonization. This article proposes key avenues for experimental validation, including high resolution structural studies of CB-OR heteromers, quantitative lipidomic mapping of eTBome distributions, live cell super resolution imaging of receptor nanoclusters, and gnotobiotic manipulations of microbial terpene synthesis. By introducing them as proposals to the scientific community and by integrating ECS/eCBome biology with olfactory receptor (OR) and microbial metabolite research, the ETS/eTBome concept offers a cohesive hypothesis for lipid-driven GPCR crosstalk and indicated non-standard targets for therapeutic modulation in cancer, neuroinflammation, and metabolic disorders.