Nucleotide sequences of two aspartic acid tRNAs from rat liver and rat ascites hepatoma.

Abstract

The nucleotide sequences of the major tRNAAsp from rat liver and a minor tRNAAsp present specifically in rat ascites hepatoma were determined by combined use of several postlabeling procedures. The sequence of rat liver tRNAAsp was determined to be pU-C-C-U-C-G-U-U-A-G-U-A-phi-A-G-U-G-G-D-G-A-G-U-A-U-C-C-C-C-G-C-U-C-manQ-U-C-A -m5C-G-C-G-G-G-A-G-A-m5C-m5C-G-G-G-G-T-phi-C-G-A-U-U-C-C-C-C-G-A-C-G-G-G-G-A-G- C-C-AOH. The nucleotide sequence of rat ascites hepatoma TRNAAsp was found to be the same as that of rat liver tRNAAsp, except that mannose-attached queuosine (manQ) present in the wobbling position of rat liver tRNAAsp was replaced by normal guanosine in rat ascites hepatoma tRNAAsp. The other modified nucleosides in the two tRNAAsp species were the same. Thus it was concluded that the new isoacceptor species of tRNAAsp that appears in the tumor tissue is due to hypomodification with respect to Q in the posttranscriptional process. The most notable feature on the sequence of the mammalian tRNAAsp is that cytidine is present in the position next to the 5'-end of the anticodon, because the only known tRNAs having cytidine in this position are cytoplasmic initiator tRNAs from multicellular eukaryotic organisms.