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
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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