Tissue-specific expression of the rat insulin receptor-related receptor gene

Characterization of genomic DNA encoding the insulin receptor-related receptor (IRR) previously revealed that the predicted IRR protein is closely related to the insulin and insulin-like growth factor-I receptor protein-tyrosine kinases. Using rat IRR genomic DNA as probe, IRR transcripts were detected by Northern blot analysis in RNA from rat kidney, stomach, and thymus, but not in RNA from other tissues, including skeletal muscle, brain, intestine, and uterus. Primer extension analysis using RNA from stomach revealed a single transcriptional start site 29 basepairs down-stream from a putative TATA box and 544 basepairs up-stream of the initiator methionine codon. Amplification of IRR cDNA by polymerase chain reaction and isolation of partial IRR cDNA clones confirmed that the IRR gene is an expressed gene.