Two human tyrosine tRNA genes contain introns

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Transfer RNAs (tRNAs) are crucial for protein synthesis.
• Introns in tRNA genes are rare and their function is not fully understood.
• Lambda-phage recombinants offer a system for studying eukaryotic gene expression.

Purpose of the Study:

• To isolate and characterize human tRNA genes from a lambda-phage recombinant.
• To investigate the structure and function of tyrosine acceptor tRNA (tRNATyr) genes.
• To assess the in vitro transcription of these tRNA genes in a mammalian cell system.

Main Methods:

• Isolation of a human lambda-phage recombinant containing multiple tRNA genes.
• Subcloning of DNA fragments into recombinant plasmids (pM6 and pM6128).
• Nucleotide sequence analysis to identify tRNA genes and introns.
• In vitro transcription assays using a HeLa cell system.

Main Results:

• A human lambda-phage recombinant with at least four tRNA genes was successfully isolated.
• Two distinct tRNATyr genes were identified within the subcloned plasmids pM6 and pM6128.
• Both identified tRNATyr genes were found to be interrupted by 21-base pair introns.
• The recombinant plasmids directed the synthesis of tRNA-sized products in the HeLa cell transcription system.

Conclusions:

• Human tRNATyr genes can be isolated and maintained in lambda-phage recombinants.
• The presence of introns in these tRNATyr genes suggests their potential functional significance.
• These findings demonstrate the utility of recombinant plasmids and cell-free systems for studying tRNA gene expression.