Nucleotide sequence comparison of the predicted first exonic region of goldfish ras gene between normal and neoplastic tissues.

The first exonic and its flanking regions of a ras-related gene in cultured erythrophoroma cells and normal liver of goldfish (Carassius auratus) were sequenced and their sequences compared. The two samples demonstrated identical sequences for the Alu I fragment of 245 nucleotides, of which 70 nucleotides might correspond to the 5'-upstream segment and 64 to the first intervening sequence, indicating that the predicted exonic region encodes from the 1st to the 37th amino acids from the N-terminal of mammalian ras protein. The length of the predicted first exon of goldfish was the same as that of mammals. There was a 5 nucleotide difference in this exonic region (length 111 nucleotides) from another previously determined ras-related sequence of normal goldfish. This difference was much smaller than that between any two of the three mammalian ras genes. Enhanced expression of ras gene was observed in erythrophoroma cells, although it was uncertain which ras gene was responsible for generation of the observed RNA.