IRS4
Description
The IRS4 (insulin receptor substrate 4) is a protein-coding gene located on chromosome X.
IRS4 is a protein encoded by the IRS4 gene in humans. It is a cytoplasmic protein with multiple potential phosphorylation sites, including tyrosine and serine/threonine. Tyrosine-phosphorylated IRS4 protein interacts with cytoplasmic signaling molecules that contain SH2 domains. The insulin receptor tyrosine kinase phosphorylates IRS4 upon receptor stimulation.
IRS4 acts as a bridge between various growth factor receptors (like insulin receptor, IGF1R, and FGFR1) and intracellular signaling molecules containing SH2 domains. It plays a role in the IGF1R mitogenic signaling pathway and promotes AKT1 signaling and BAD phosphorylation during insulin stimulation without activating RPS6KB1 or inhibiting apoptosis. IRS4 interacts with GRB2 to enhance insulin-stimulated mitogen-activated protein kinase activity. It might be involved in nonreceptor tyrosine kinase signaling in myoblasts and plays a crucial role in hepatoblastoma cell proliferation and differentiation through EPHB2 activation upon IGF1 stimulation. It participates in signal transduction in response to insulin, and to a lesser extent IL4 and GH, contributing to mitogenesis. IRS4 contributes to growth, reproduction, and glucose homeostasis. It might act as a negative regulator of the IGF1 signaling pathway by suppressing the function of IRS1 and IRS2.
IRS4 is also known as CHNG9, IRS-4, PY160.
