Molecular model of the glmS ribozyme complexed with glucosamine-6-phosphate. This molecule functions as both a ribozyme, an RNA (ribonucleic acid) with enzymatic activity, and a riboswitch, a segment of RNA that acts a regulator of gene expression. Binding of glucosamine-6-phosphate, the product of the glms enzyme, cleaves the ribozyme leading to lower production of the enzyme when glucosamine-6-phosphate concentrations are high.