Human skeletal muscle insulin receptor substrate-1. Characterization of the cDNA, gene, and chromosomal localization.
Insulin receptor substrate-1 is a major substrate of insulin receptor Tyr kinase. We have now cloned the IRS-1 cDNA from human skeletal muscle, one of the most important target tissues of insulin action, localized and cloned the human IRS-1 gene, and studied the expression of the protein in Chinese hamster ovary cells. Human IRS-1 cDNA encodes a 1242 amino acid sequence that is 88% identical with rat liver IRS-1. The 14 potential Tyr phosphorylation sites include 6 Tyr-Met-X-Met motifs and 3 Tyr-X-X-Met motifs that are completely conserved in human IRS-1. Human IRS-1 has > 50 possible Ser/Thr phosphorylation sites and one potential ATP-binding site close to the NH2-terminal. The human IRS-1 gene contains the entire 5'-untranslated region and protein coding region in a single exon and was localized on chromosome 2 q36-37 by in situ hybridization. By Northern blot analysis, IRS-1 mRNA is rare and consists of two species of 6.9 and 6 kilobase. By using quantitative polymerase chain reaction after reverse transcription of total RNA from human fetal tissues, IRS-1 mRNA could be identified in all tissues. When human IRS-1 cDNA was expressed in Chinese hamster ovary cells, the protein migrated between 170,000-180,000 M(r) in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was rapidly Tyr phosphorylated upon insulin stimulation. Thus, IRS-1 is widely expressed and highly conserved across species and tissues.(ABSTRACT TRUNCATED AT 250 WORDS)
Pubmed ID: 8513971 RIS Download
Amino Acid Sequence | Animals | Base Sequence | CHO Cells | Chromosome Mapping | Chromosomes, Human, Pair 2 | Cloning, Molecular | Cricetinae | DNA | Fetus | Gene Expression | Genomic Library | Humans | In Situ Hybridization | Insulin Receptor Substrate Proteins | Liver | Molecular Sequence Data | Muscles | Oligodeoxyribonucleotides | Phosphoproteins | Polymerase Chain Reaction | RNA, Messenger | Rats | Sequence Homology, Amino Acid | Transcription, Genetic | Transfection