The structure of tRNA 5 Lys from Drosophila melanogaster

Human glutamate tRNA forms stable hybrids in vitro with 28S ribosomal RNA

A human glutamate tRNA has been shown to form stable hybrids with 28S ribosomal RNA. This tRNA was purified from HeLa cell cytoplasmic RNA by RNA-RNA solution hybridization followed by the isolation of tRNA-28S rRNA complexes by hybridization-selection with ribosomal DNA or by recovery of the 28S peak from formamide-sucrose gradients. The single hybridizing tRNA species was identified as tRNAGluCUC by sequencing: pU-C-C-C-U-G-G-U-G-m2G-U-C-phi-A-G-U-G-G-D-phi-A-G-G-A-U-U- C-G-G-C-G-C-U-C-U-C-A-C-C-G-C-G-G-C-m5C-m5C-G-G-G-Tm-phi-C-G-A- U-U-C-C-C-G-G-U-C-A-G-G-G-A-A-C-C-AOH. Computer analysis located a nucleotide sequence near the middle of human 28S rRNA which is complementary to 15-26 nucleotides between residues 20 and 50 of this tRNA. An interaction between this tRNA and 28S rRNA suggests that tRNAGluCUC may have functions in the cell in addition to translation.

Structural relationship between tRNALys2 and tRNALys4 from mouse lymphoma cells

Mouse lymphoma cells have three major isoaccepting lysine tRNAs. Two of these isoacceptors, tRNALys2 and tRNALys4, were sequenced by rapid gel or chromatogram readout methods. They have the same primary sequence but differ in two modified nucleotides. tRNALys4 has an unmodified uridine replacing one dihydrouridine and an unidentified nucleotide, t6A*, replacing t6A. This unidentified nucleotide is not a hypomodified form of t6A. Thus, tRNALys4 is not a simple precursor of tRNALys2. Both tRNAs have an unidentified nucleotide, U**, in the third position of the anticodon. Also, partial sequences of minor homologs of tRNALys2 and tRNALys4 were obtained. The distinctions between tRNALys2 and tRNALys4 may be part of significant cellular roles as illustrated by the differential effects of these isoacceptors on the synthesis by lysyl-tRNA synthetase of diadenosine-5',5'''-P1,P4-tetraphosphate, a putative signal in DNA replication.

Lysine tRNAs from rat liver: lysine tRNA sequences are highly conserved

The two major lysine tRNAs from rat liver, tRNA2Lys and tRNA5Lys, were sequenced by rapid gel or chromatogram readout methods. The major tRNA2Lys differs from a minor form only by a base pair in positions 29 and 41; both tRNAs have an unidentified nucleotide, U**, in the third position of the anticodon. Although highly related, the major tRNA2Lys and tRNA5Lys differ in four base pairs and four unpaired nucleotides, including the first position of the anticodons, but have the same base pair in positions 29 and 41. The three tRNAs maintain a m2G-U pair in the acceptor stem. Detection of this m2G is in contrast to other reports of lysine tRNAs. Sequences of lysine tRNAs are strongly conserved in higher eukaryotes.