riboswitch

A riboswitch is a segment of messenger RNA (mRNA) that can regulate gene activity by changing its shape in response to specific molecules, called ligands. When the ligand binds to the riboswitch, it causes the mRNA to adopt a different structure, which can turn gene expression on or off. This mechanism allows cells to quickly adjust the production of proteins based on the availability of certain nutrients or molecules, acting like a molecular switch that helps maintain cellular balance and efficiency without needing proteins to control the process.