G(olf) α is a G-protein originally believed to mediate signal transduction exclusively within the olfactory neuroepithelium and subsequently found to be a major stimulatory G-protein in the basal ganglia. Here we present evidence that G(olf) α is expressed in several other tissues. The human isoform of G(olf) α was isolated from two human insulinoma cDNA libraries. Comparison of the human sequence with rat G(olf) α shows 91% nucleotide identity (within the coding region) and 99% identity at the amino acid level. Northern and reverse transcriptase-polymerase chain reaction analyses indicated that G(olf) α is expressed in all human insulinomas examined thus far as well as in normal pancreatic islets. G(olf) α mRNA was also detected in testis, retina, brain, and liver. Western blot analysis of various mouse tissues demonstrated that the level of G(olf) α protein in islets is lower than that in the olfactory neuroepithelium and other parts of the brain; its expression in retina, lung, and spleen was moderately higher than that in islets, and its expression in testis approached that in olfactory neuroepithelium. G(olf) α was also detected by immunohistochemistry in mouse islets, human insulinomas, the epithelial lining of mouse epididymis, photoreceptor cells of mouse retina, and mouse lung alveoli. These findings suggest a role for G(olf) α in a diverse population of cells located outside the olfactory neuroepithelium and central nervous system.
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