IRS1

Insulin receptor substrate 1 (IRS-1) is a signalling adapter protein that in humans is encoded by the IRS-1 gene. It contains a single pleckstrin homology (PH) domain at the N-terminus and a PTB domain ca. 40 residues downstream of this. Together with IRS2, IRS3 (pseudogene) and IRS4, it is homologous to the Drosophila protein chico, whose disruption extends the median lifespan of flies up to 48%. Similarly, Irs1 mutant mice experience moderate life extension and delayed age-related pathologies.

Function

Insulin receptor substrate 1 plays a key role in transmitting signals from the insulin and insulin-like growth factor-1 (IGF-1) receptors to intracellular pathways PI3K / Akt and Erk MAP kinase pathways.

Tyrosine phosphorylation of the insulin receptors or IGF-1 receptors, upon extracellular ligand binding, induces the cytoplasmic binding of IRS-1 to these receptors, through its PTB domains. Multiple tyrosine residues of IRS-1 itself are then phosphorylated by these receptors. This enables IRS-1 to activate several signalling pathways, including the PI3K pathway and the MAP kinase pathway.