tRNAhan

tRNAhan is a term used in genetic engineering and speculative biology to denote a transfer RNA molecule engineered to participate in translation in a way distinct from natural tRNAs. In discussions and educational examples, tRNAhan is designed to recognize a predefined codon in a synthetic genetic system and to deliver a chosen amino acid, often a noncanonical one, thereby enabling expansion of the genetic code.

Like canonical tRNAs, tRNAhan is envisioned to adopt the characteristic cloverleaf structure, with an acceptor stem for aminoacylation, a D arm, an anticodon loop for codon recognition, a TψC arm, and a 3' CCA terminus for amino acid attachment. In engineered contexts, its anticodon and identity elements are modified to ensure selective pairing with the target codon and proper charging by a corresponding aminoacyl-tRNA synthetase, ideally while remaining orthogonal to the host’s native tRNA pool.

Functionally, tRNAhan is used to study translation fidelity, codon reassignment, and the incorporation of nonstandard amino acids into proteins. Such tRNA variants can support site-specific incorporation of novel residues, enabling new protein functions, while providing a testbed for understanding cross-talk between tRNA charging, ribosome decoding, and cellular fitness.

In practice, introducing tRNAhan into a living system requires careful design of the tRNA gene, processing signals, and compatible synthetases to minimize mischarging and cross-reactivity. Research remains largely in the realm of synthetic biology and theoretical models, with emphasis on safety and controllability.