Rabbit calcium-sensing receptor (CASR) gene: chromosome location and evidence for related genes

Diverse cellular functions are regulated by the calcium-sensing receptor, e ncoded by the CASR gene, which plays an important role in calcium homeostas is. Here we provide the sequence for exon VII of the rabbit CASR gene and s how that it is 91% identical to the human gene at the nucleotide level, and 95% identical at the amino acid level. The gene was mapped by fluorescence in situ hybridization, using a cosmid isolated from a genomic library, to chromosome 14q11 and this was confirmed independently by PCR amplification of flow sorted chromosomes. In addition, the cosmid detected sites with low er frequencies on four other chromosomes: 3q, 5p, 8p,and 13p. Two of these sites (5p and 13p) were also detected by a related but unidentical cosmid, and map to regions that are homologous to the mouse calcium-sensing recepto r related sequences (Casr-rs); suggesting that they may represent CASR-rela ted sequences in the rabbit. The data support the presence of a family of g enes related to the calcium-sensing receptor in the G-protein coupled recep tor (GPCR) superfamily, as well as extend the existing knowledge of homolog y for several human and rabbit chromosomes.