Expression of the Drosophila ras2/cs1 Gene Pair during Development
Several homologs of vertebrate proto-oncogenes have been detected in D.melanogaster — abl, src, ras, myb, raf, erb-B (DER), fps (reviewed in Shilo, 1987), int-1 (wingless. Rijsewijk et al, 1987), rel (dorsal. Steward, 1987), TGF-B (decapentaplegic. Padgett et al, 1987) and jun and fos (Djra and Dfra, Perkins et al, 1988). Three homologs of the viral Ha-ras gene were also isolated. They were termed Ras1, Ras2, and Ras3 (Lindsley and Zimm, 1990) and mapped to regions 85D, 64B, and 62B, respectively, on the 3rd chromosome (Neuman-Silberberg et al, 1984). Synonymous names are Dras1, Dras2, and Dras3 (Neuman-Silberberg et al, 1984), or Dmras85D and Dmras64B (Mozer et al, 1985; Brock, 1987). Analysis of the nucleotide sequence of cloned genomic and cDNA sequences suggests that among the three Drosophila ras genes Ras1 is the genuine homolog of the human Ha-, Ki-, and N-ras genes. The Ras2 gene is more similar to the human R-ras gene family and the Drosophila ras3 is similar to the human rap gene family (Chardin et al, 1989). For example, in the 3–79 amino acids the human Ha-Ras protein has 100 percent homology with the Drosophila Ras1 protein and only 79 percent with the Drosophila Ras2 protein which, In the same region, has 87 percent homoloy with the R-ras protein. The homology between the Drosophila Ras1 and Ras2 proteins is significantly lower (78 percent) than the homology between them and their human counterparts.
KeywordsImaginal Disc Bidirectional Promoter Ventral Ganglion Cell BioI Transcription Fusion
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