The function of the yjdF gene is unknown, but the protein that it is predicted to encode is classified by the Pfam Database as DUF2992.
[2] The moderately complex secondary structure and nucleotide positions conserved in the yjdF RNA motif and the fact that it is likely to be present in 5' UTRs led to the hypothesis that yjdF RNAs function as riboswitches.
One yjdF RNA is found instead in the presumed 5' UTR of genes encoding enzymes involved in the synthesis of nicotinamide adenine dinucleotide (NAD+).
These RNAs lack a region of the otherwise conserved yjdF RNA motif and might be non-functional, or conform to a distinct structure that achieves the same function.
If yjdF RNAs are riboswitches, this other RNA might bind a distinct small molecule ligand.