tRNAn

tRNAn is not a standard term in molecular biology. In most literature, the familiar adaptor molecule is transfer RNA, abbreviated tRNA. The label tRNAn may appear in some texts as a variant or shorthand for the tRNA gene set or the cellular tRNA pool. This article uses tRNAn to refer to the conventional tRNA concept in a genome- or cell-wide context.

Structure and maturation of tRNAn follows the general tRNA design. tRNA molecules typically exhibit a cloverleaf secondary structure with an acceptor stem at the 3' end, a D loop, an anticodon loop, and a TψC loop. They fold into an L-shaped three-dimensional form that positions the amino acid attachment site and anticodon for decoding the genetic code. Mature tRNA is about 70–76 nucleotides long, and a CCA sequence at the 3' terminus is added post-transcriptionally to serve as the amino acid attachment site.

Function and charging are central to tRNAn’s role in translation. Aminoacyl-tRNA synthetases catalyze the attachment of the correct amino acid to the 3' end of each tRNA, creating aminoacyl-tRNA. The anticodon recognizes mRNA codons, with wobble base-pairing allowing certain flexibility at the third codon position. The resulting aminoacyl-tRNA delivers the growing polypeptide chain during ribosomal synthesis, enabling accurate interpretation of the genetic code.

Genomic diversity and processing are characteristic of tRNAn in cells. tRNA genes are numerous and dispersed, with isoacceptors encoding the same amino acid but different anticodons. Some organisms harbor mitochondrial or chloroplast tRNAs. Maturation involves trimming precursor transcripts, intron splicing in some species, and extensive post-transcriptional nucleotide modifications that affect stability and decoding efficiency.

See also: transfer RNA, anticodon, aminoacyl-tRNA synthetase, wobble base pairing.