CLONING OF A CDNA-ENCODING A 190-KDA INSULIN-RECEPTOR SUBSTRATE-1-LIKE PROTEIN OF SIMIAN COS CELLS

Major insulin signals such as stimulation of glucose uptake and DNA sy nthesis and modification of hexose metabolism are mediated by the tyro sine-phosphorylated insulin receptor substrate-1 (IRS-1; pp 180) in ma ny species of cells. We cloned cDNA encoding a 190-kDa IRS-1-like prot ein (pp190) in simian COS cells and which is slightly larger than IRS- 1 (pp180) of human, rat, and mouse cells. The deduced amino acid seque nce of COS pp190 consisted of 1251 amino acids and was 96.4%, 87.9% an d 88.7% identical to human, mouse and rat IRS-1. The COS pp190 bound t o SH2 (src-homology 2) domains of p85, Grb2/Ash, and SH-PTP2, as did I RS-1. In IRS-1-knockout mice, insulin signals are thought to be mediat ed by IRS-2 (pp190),which is an alternative signaling molecule and is slightly larger than IRS-1. However, the COS pp190 may be a simian hom ologue of IRS-1, but not of IRS-2. The results of Southern blotting su ggested the possibility that Chinese hamster ovary (CHO) cells have no t only the IRS-I gene but also a gene related to the COS pp190. (C) 19 95 Academic Press, Inc.