INHIBITION OF RAF MAPK SIGNALING IN XENOPUS OOCYTE EXTRACTS BY RAF-1-SPECIFIC PEPTIDES/

Raf-1 is an upstream element of the mitogen-activated protein kinase ( MAPK) pathway which leads to cell proliferation and differentiation. I n this study Raf-1 derived peptides comprising the conserved amino aci d residues Arg89 and Ser259, involved in binding of activated Ras and 14-3-3 proteins, respectively, were shown to interfere with MAPK activ ation in extracts from immature Xenopus oocytes. Lipids prepared from oocyte extracts can stimulate MAPK in a Ras- and protein kinase C-inde pendent manner. This lipid-induced MAPK activation is blocked by a Raf -1 derived peptide comprising Ser259. (C) 1996 Academic Press, Inc.