Isolated endosomes from quiescent rat liver contain the signal transduction machinery - Differential distribution of activated Raf-1 and Mek in the endocytic compartment

In this study we identify the molecules involved in the MAPK signal transduction pathway (Ras, Raf-1, Mek, Mek-P and MAPK) in highly purified endosomal fractions isolated from rat liver. Biochemical analysis shows that only the early-sorting endocytic compartment contains activated Raf-1 and Mek, Finally, the exogenous administration of EGF led to redistribution of Raf-1 from the caveolin-enriched plasma membrane into the endosomes, (C) 1998 Federation of European Biochemical Societies.