A full length cDNA encoding the rat Ca²⁺ sensing receptor (CaSR) expressed in dorsal root ganglia (DRG) was identified using 5' RACE and primer extension; and cloned into the plasmid vector pCR3.1. The DNA sequence of the DRG CaSR was 99% homologous with published rat kidney CaSR in the coding region and 247 bp upstream of the start codon, but showed little homology 5' to this site which maps to exonic junction I/II; suporting the hypothesis that the DRG CaSR message arises as a tissue specific splice variant. Western blot revealed a doublet of 140 and 160 kDa in a thyroparathyroid preparation and a single 140 kDa band in DRG. Deglycosylation using N-glycanase increased the mobility of CaSR protein from both DRG and thyroparathyroid, while endo-H was without effect. A DRG CaSR-pEGFP fusion product was constructed and when transfected into HEK-293 cells was distributed at the cell membrane and resulted in extracellular Ca²⁺ (0.5-3 mmol/L)-evoked increases in intracellular Ca²⁺ which in some instances exhibited oscillatory behavior. It is concluded that DRG CaSR cDNA arises from tissue specific alternative splicing of a single gene, the amino acid sequence of DRG CaSR is homologous to other known CaSRs and undergoes differential post-translational processing relative to the thyroparathyroid CaSR, and the receptor is functionally active when transfected into a human-derived cell line.