β-Amanitin is primarily used in scientific research to study the mechanisms of RNA polymerase II inhibition. It is a potent toxin that selectively binds to and inhibits this enzyme, making it a valuable tool for understanding transcription processes in eukaryotic cells. Researchers utilize it to investigate cell death pathways, particularly apoptosis, and to explore the effects of transcriptional arrest on cellular functions. Additionally, β-Amanitin is employed in the development of targeted therapies, such as antibody-drug conjugates, where its toxic properties are harnessed to selectively destroy cancer cells. Its application in molecular biology and toxicology has provided critical insights into gene expression regulation and cellular responses to stress.