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.
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Departament de Biologia Cellular, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Facultat de Medicina, Universitat de Barcelona, Spain.
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D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D051242:Caveolin 1; D022461:Caveolins; D002458:Cell Fractionation; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D004815:Epidermal Growth Factor / Q000494:pharmacology; D008099:Liver / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008954:Models, Biological; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D018631:ras Proteins / Q000378:metabolism
C495537:Cav1 protein, rat; D051242:Caveolin 1; D022461:Caveolins; D008565:Membrane Proteins; D004815:Epidermal Growth Factor; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D018631:ras Proteins