[1] The motif consists of two conserved stem-loops whose terminal loops contain the RNA sequence ACGR, where R represents either A or G. Mini-ykkC RNAs are widespread in Pseudomonadota, but some are predicted in other phyla of bacteria.

It was expected that the RNAs are cis-regulatory elements, because they are typically located upstream of protein-coding genes.

The complex structure and many conserved nucleotides found in the ykkC-yxkD leader are not present in the mini-ykkC RNA motif.

Despite this, it was shown that each of the mini-ykkC two stem-loop structures directly binds free guanidine.

Therefore, mini-ykkC RNA motif represents a distinct class of guanidine-sensing RNAs called Guanidine-II riboswitch.