Cactin, a conserved protein that interacts with the Drosophila I kappa B protein Cactus and modulates its function

Rel transcription factors function in flies and vertebrates in immunity and development. Although Rel proteins regulate diverse processes, the control of their function is conserved. In a two-hybrid screen for additional comp onents of the pathway using the Drosophila I-kappa B protein Cactus as a ba it, we isolated a novel coiled-coil protein with N-terminal Arg-Asp (RD)- l ike motifs that we call Cactin. Like the other components of this pathway, Cactin is evolutionarily conserved. Over-expression of cactin in a cactus(A 2) heterozygous background results in the enhancement of the cactus phenoty pe. Both the embryonic lethality and ventralization are strongly increased, suggesting that cactin functions in the Rel pathway controlling the format ion of dorsal-ventral embryonic polarity. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.