CHARACTERIZATION OF THE G-PROTEIN LINKED ORPHAN RECEPTOR GPRN1 RDC1/

Site specific antibodies were raised against the second intracellular loop of the G-protein coupled orphan receptor GPRN1 for analysis of re ceptor protein expression from a number of sources. Immunoblot analyse s showed GPRN1 to be a 60 kDa membrane bound glycoprotein. It was foun d in AR4-2J, PC12 and SK-N-MC cell lines. High amounts of GPRN1 were f ound in rat stomach, liver, lung, brain, small intestine and pancreas, with lower amounts in spleen and kidney: none was detectable in rat h eart. This distribution differs markedly from that of the closely rela ted orphan receptor RDC1. The receptor shows high evolutionary conserv ation: immunoreactive 60 kDa GPRN1 was detected in membrane glycoprote in fractions from the livers of rat, toad, chick, stingray and shark. It is therefore predicted that GPRN1 and RDC1 represent two tissue spe cific subtypes of a 60 kDa receptor for a ligand which has likely been highly conserved throughout evolution and which is active upon many o rgans of the body. (C) 1994 Academic Press, Inc.