Identification and characterization of a novel human vanilloid receptor-like protein, VRL-2

Remarkable progress has been made recently in identifying a new gene family related to the capsaicin (vanilloid) receptor, VR1. Using a combination of in silico analysis of expressed sequence tag (EST) databases and conventio nal molecular cloning, we have isolated a novel vanilloid-like receptor, wh ich we call VRL-2, from human kidney. The translated gene shares 46% and 43 % identity with VR1 and VRL-1, respectively, and maps to chromosome 12q23-2 4.1, a locus associated with bipolar affective disorder. VRL-2 mRNA was mos t strongly expressed in the trachea, kidney, and salivary gland. An affinit y-purified antibody against a peptide incorporating the COOH terminal of th e receptor localized VRL-2 immunolabel in the distal tubules of the kidney, the epithelial linings of both trachea and lung airways, serous cells of s ubmucosal glands, and mononuclear cells. Unlike VR1 and VRL-1, VRL-2 was no t detected in cell bodies of dorsal root ganglia (DRG) or sensory nerve fib ers. However, VRL-2 was found on sympathetic and parasympathetic nerve fibe rs, such as those innervating the arrector pili smooth muscle in skin, swea t glands, intestine, and blood vessels. At least four vanilloid receptor-li ke genes exist, the newest member, VRL-2 is found in airway and kidney epit helia and in the autonomic nervous system.