Molecular dissection of a transfer RNA and the basis for its identity

The recognition of transfer RNAs (tRNAs) by aminoacyl tRNA synthetases establishes the connection between amino acids and trinucleotides. However, for E. coli alanine tRNA the trinucleotide sequence which specifies alanine is not important for recognition. Instead a single base pair is a major determinant for the identity of this tRNA. Even a synthetic RNA microhelix with seven base pairs can be aminoacylated if it includes the major determinant.