Characterization of Maternal and Zygotic D-Raf Proteins: Dominant Negative Effects on Torso Signal Transduction

AUTOR(ES)

Radke, K.

RESUMO

The maternal D-raf serine/threonine kinase acts downstream of Torso (Tor) for specification of cell fates at the embryonic termini. D-raf activity is also required in other signal transduction pathways and consistent with its pleiotropic role, we find accumulation of a 90-kD D-raf protein throughout embryonic development. We also characterize the accumulation of maternal D-raf proteins in 0-2-hr embryos derived from females with germ cells lacking D-raf activity. Accumulation of a 90-kD or truncated mutant D-raf protein is observed for some of these embryos, while others lack the maternal D-raf protein. Then, to determine whether rescue of the Tor pathway is influenced by pools of nonfunctional maternal D-raf, wild-type D-raf mRNA was injected into embryos that inherit maternal stores of inactive 90-kD or truncated D-raf protein. For embryos lacking the maternal D-raf protein, a high level of terminal rescue is obtained. In contrast, rescue is reduced or not observed for embryos that accumulate mutant maternal D-raf proteins. These findings suggest that mutant forms of D-raf may deplete the embryo of a positive activator and/or form inactive protein complexes that affect rescue of the Tor pathway.

Documentos Relacionados

• Biochemical analysis of torso and D-raf during Drosophila embryogenesis: implications for terminal signal transduction.
• A Dominant-Negative Herpesvirus Protein Inhibits Intranuclear Targeting of Viral Proteins: Effects on DNA Replication and Late Gene Expression
• Raf-1 N-terminal sequences necessary for Ras-Raf interaction and signal transduction.
• Genetic and molecular analyses of mutations involved in Drosophila raf signal transduction.
• Hedgehog signal transduction proteins: contacts of the Fused kinase and Ci transcription factor with the Kinesin-related protein Costal2