The Activity of D-raf in Torso Signal Transduction Is Altered by Serine Substitution, N-Terminal Deletion, and Membrane Targeting
Autor: | John R. Fabian, Linda Ambrosio, Deborah K. Morrison, Kwang-Hyun Baek, Frank Sprenger |
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Rok vydání: | 1996 |
Předmět: |
Embryo
Nonmammalian Molecular Sequence Data PIM1 AKT2 Protein Serine-Threonine Kinases Spodoptera Biology Serine 03 medical and health sciences 0302 clinical medicine Proto-Oncogene Proteins Morphogenesis Animals Drosophila Proteins Humans Phosphorylation Kinase activity Molecular Biology Sequence Deletion 030304 developmental biology Serine/threonine-specific protein kinase 0303 health sciences Alanine Base Sequence Kinase Gene Expression Regulation Developmental Membrane Proteins Receptor Protein-Tyrosine Kinases Cell Biology Nucleopolyhedroviruses Recombinant Proteins Cell biology Proto-Oncogene Proteins c-raf Drosophila melanogaster Biochemistry Mutagenesis Site-Directed Signal transduction Protein Processing Post-Translational 030217 neurology & neurosurgery Signal Transduction Developmental Biology |
Zdroj: | Developmental Biology. 175(2):191-204 |
ISSN: | 0012-1606 |
DOI: | 10.1006/dbio.1996.0107 |
Popis: | TheRaffamily of serine/threonine kinases are essential components in many receptor tyrosine kinase-mediated signal transduction pathways. Here, we analyze the function of D-raf in the Torso (Tor) pathway required to specify cellular fates at the embryonic poles. Using mutant embryos lacking endogenous D-raf protein, we show that D-raf's serine/threonine kinase activity is essential for its role in Tor signal transduction and that human Raf-1 will substitute for D-raf in this pathway. After Tor activation, D-raf becomes hyperphosphorylated. We identified two putative serine phosphorylation sites (S388 and S743) in SF9 cells and demonstrate that S743 or its phosphorylation is essential for D-raf function in embryos. Alanine substitution at S388, N-terminal truncation, or targeted membrane association permits transmission of the Torso signal by D-raf, but these D-raf molecules differ in their rescuing potential and relative biological activity. Membrane-targeted D-raftor4021showed the highest level of activity, followed by alanine-substituted D-rafS388Aand N-terminal-truncated D-rafΔ445. Since the activity profiles for these altered forms of D-raf are distinct, these findings indicate that each structural modification differentially affects the regulation and/or propagation of the Tor signal by these mutant D-raf proteins. |
Databáze: | OpenAIRE |
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