A. Pham et al., THE SUPPRESSOR OF FUSED GENE ENCODES A NOVEL PEST PROTEIN INVOLVED INDROSOPHILA SEGMENT POLARITY ESTABLISHMENT, Genetics, 140(2), 1995, pp. 587-598
Suppressor of fused, Su(fu), was identified as a semi-dominant suppres
sor of the putative serine/threonine kinase encoded by the segment pol
arity gene fused in Drosophila melanogaster. The amorphic Sw(fu) mutat
ion is viable, shows a maternal effect and displays no phenotype by it
self. Su(fu) mutations are often found associated to karmoisin (kar) m
utations but two complementation groups can be clearly identified. By
using a differential hybridization screening method, we have cloned th
e Su(fu) region and identified chromosomal rearrangements associated w
ith Su(fu) mutations. Two classes of cDNAs with Similar developmental
patterns, including a maternal contribution, are detectable in the reg
ion. Transformation experiments clearly assigned the Su(fu)(+) functio
n to one of these transcription units while the other one can be most
likely assigned to the kar(+) function. Surprisingly the 5' end of the
kar RNA mapped within the 3' untranslated region of the Su(fu) transc
ribed sequence. The Su(fu) gene encodes a 53-kD protein, which contain
s a PEST sequence and shows no significant homologies with known prote
ins. Genetic analysis shows that proper development requires a fine tu
ning of the genetic doses of fu and Su(fu) both maternally and zygotic
ally. These results, together with previous genetic and molecular data
, suggest that fused and Suppressor of fused could act through a compe
titive posttraductionnal modification of a common target in the hedgeh
og signaling pathway.