Rasta is a TCF binding factor that is essential for wingless signal transduction in Drosophila. B.J. Thompson , F.M. Townsley , R. Rosin-Arbesfeld , H.K. Musisi , M. Bienz. Division of Cell Biology, MRC-LMB, Cambridge, England.

   A genetic screen for modifiers of Armadillo signalling in Drosophila isolated two mutants in a novel PHD-finger gene we have named Rasta. Analysis of the Rasta mutant phenotype in somatic and germ-line clones demonstrates that Rasta is an essential and dedicated component of the wingless signalling pathway. Rasta is required for activation of wingless target genes but appears to act downstream of Armadillo stabilisation. Biochemical analysis indicates that Rasta binds directly to dTCF. Thus, Rasta is a second factor, alonside dTCF, that is essential for Armadillo to transduce wingless signals.