A MURINE CDC25 RAS-GRF-RELATED PROTEIN IMPLICATED IN RAS REGULATION/

A partial cDNA encoding a novel putative p2, ras guanine nucleotide re lease-inducing factor (GRF), GRF2, was amplified from murine embryonic stem cells. The presumptive catalytic region of GRF2 is related to th e yeast Ras GRF encoded by CDC25. GRF2 is 80% identical to murine CDC2 5Mm/ras-GRF, but is more similar to yeast CDC25 than to other ras GRFs related to the Drosophila son of sevenless gene product. A 9-kb GRF2 messenger RNA was highly expressed in brain, but GRF2-specific antibod ies recognized apparent GRF2 proteins in various mouse tissues in addi tion to brain. Thus GRF2 represents a novel widely-expressed protein t hat is highly related to CDC25Mm/ras-GRF, at least in its catalytic do main. Both GRF2 and CDC25Mm/ras-GRF are expressed in murine embryonic stem cells, suggesting that different Ras activators may regulate ras- dependent proliferation and differentiation in early mouse development . (C) 1993 Wiley-Liss, Inc.