A NOVEL ORPHAN G-PROTEIN-COUPLED RECEPTOR PRIMARILY EXPRESSED IN THE BRAIN IS LOCALIZED ON HUMAN CHROMOSOMAL BAND 2Q21

A human hippocampus cDNA library was screened with a probe obtained fr om degenerate RT-PCR aimed at P2Y-homologous sequences. A positive clo ne, designated hip4, was identified containing an open reading frame o f 1,020 bp that had been previously detected in a published genomic cl one called R12. Subsequent screening of a human fetal brain cDNA libra ry yielded a splice variant with a 1,104-bp open reading frame, which was named fb1. Both variants display the seven-transmembrane topology that is typical for G protein-coupled receptors. Probing a human multi tissue northern blot revealed two brain-specific transcripts of 2.3 an d 6.3 kb, respectively. Northern blot analyses with specific fragments confirmed that the two transcripts are generated by alternative polya denylation yielding two different 3' untranslated regions. A genomic c lone from the corresponding gene was isolated and mapped to human chro mosomal band 2q21 by fluorescence in situ hybridization.