Cloning and sequencing of the complete cDNA encoding the human insulin receptor related receptor

The insulin receptor related receptor (IRR) is a heterotetrameric transmemb rane receptor with intrinsic tyrosine kinase activity. The IRR shares large homology with the insulin and the insulin-like growth factor-1 (IGF-I) rec eptor with regard to amino acid sequence and protein structure. So far, onl y a partial human sequence containing the complete 3' end has been reported , although the full-length human IRR cDNA had been used for transfection st udies and functional analysis of the receptor. We have isolated a full-leng th human IRR cDNA and report on the 5' translated and untranslated region o f the human IRR gene. The full length IRR sequence contains 4150 bases and shares a high degree of homology with the guinea pig IRR cDNA sequence and rat IRR sequences that had been reported earlier on by others. Sequencing o f the IRR cDNA revealed that the human IRR cDNA contains 341 bases correspo nding to the IRR 5' end in addition to the bases that had been reported on before. Also, this sequence contains the start codon of translation. The fu ll length cDNA for the human IRR can now be used for functional expression studies and to elucidate the nature of the ligand for this receptor type.