Structural domains comprising this superfamily share the structure of the C-terminal domain of threonylcarbamoyl-AMP synthases, including Sua5 from Saccharomyces cerevisiae amongst others. These enzymes are involved in the formation of a threonylcarbamoyl group on adenosine at position 37 (t6A37) in tRNAs decoding ANN codons. This process allow stabilization of the interaction between the codon and the anticodon on the ribosome to increase translational accuracy. that read codons beginning with adenine PMID:19287007.

This C-terminal domain adopts the Rossmann fold and it is thought to be involved in GTP and/or tRNA binding based on structural similarity with both GTP and tRNA binding proteins PMID:21538543.