G protein-coupled receptors (GPRs) are a protein family of transmembrane receptors that transmit an extracellular signal (ligand binding) into an intracellular signal (G protein activation). GPR signaling is an ancient evolutionarily mechanism used by all eukaryotes to sense environmental stimuli and mediate cell-cell communication. GPRs have seven membrane-spanning domains and the extracellular domains are often glycosylated. These extracellular loops also contain two highly conserved cysteine residues which create disulfide bonds to stabilize the receptor structure. GPR26 (G-protein coupled receptor 26) is a 337 amino acid protein that is primarily expressed in regions of the brain. GPR26 is characterized as an ‘orphan’ G protein-coupled receptor, which is a receptor that binds an unidentified natural ligand. Due to evidence of GPR26 being downregulated in glioblastomas, it has been suggested that GPR26 may be a suppressor of early glioma development.