Tamo selectively modulates nuclear import in Drosophila.
BACKGROUND
The NF-kappaB/Rel pathway functions in the establishment of dorsal-ventral polarity and in the innate humoral and cellular immune response in Drosophila. An important aspect of all NF-kappaB/Rel pathways is the translocation of the Rel proteins from the cytoplasm to the nucleus, where they function as transcription factors.


RESULTS
We have identified a new protein, Tamo, which binds to Drosophila Rel protein Dorsal, but not to Dorsal lacking the nuclear localization sequence. Tamo does not bind to the other Drosophila Rel proteins, Dif and Relish. The Tamo-Dorsal complex forms in the cytoplasm and Tamo also interacts with a cytoplasmically orientated nucleoporin. In addition Tamo binds the Ras family small GTPase, Ran. Tamo functions during oogenesis and, based on phenotypic analysis, controls the levels of nuclear Dorsal in early embryos. It further regulates the accumulation of Dorsal in the nucleus after immune challenge.


CONCLUSIONS
Tamo has an essential function during oogenesis. Tamo interacts with Dorsal and proteins that are part of the nuclear import machinery. We propose that tamo modulates the levels of import of Dorsal and other proteins.
Minakhina
Svetlana
S
Waksman Institute, Department of Molecular Biology and Biochemistry, NJ Cancer Center, Rutgers University, 190 Frelinghuysen Road, Piscataway, NJ 08854-8020, USA.
Yang
Jun
J
Steward
Ruth
R
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004330:Drosophila / Q000196:embryology / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D019913:Nuclear Localization Signals / Q000502:physiology; D009687:Nuclear Proteins / Q000378:metabolism; D009866:Oogenesis / Q000502:physiology; D010053:Ovary / Q000196:embryology / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D016328:NF-kappa B; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D010750:Phosphoproteins; D014157:Transcription Factors; C062236:dl protein, Drosophila