G protein-coupled receptors (GPRs, or GPCRs) contain 7 hydrophobic transmembrane domains embedded in hydrophilic intra- and extracellular loops and transduce a variety of hormone, endogenous peptide, and neurotransmitter signals into intracellular effects via G proteins. GRP30 is a member of this family and is an orphan receptor. GPR30 expression has been reported in brain, breast carcinoma, blood, bone marrow, CNS, heart, liver, lung, lymph node, placenta, and spleen. In brain, GPR30 is expressed as a 2.8 kb transcript in basal forebrain, frontal cortex, thalamus, hippocampus, caudate and putamen. However, unlike other known G protein-coupled receptors, GPR30 localizes to the endoplasmic reticulum, where it specifically binds estrogen and estrogen derivatives.
