Tetramethylrhodamine-6-maleimide is widely used as a fluorescent labeling agent in biochemical and cellular research. It is particularly effective for tagging proteins, peptides, and other biomolecules due to its high fluorescence intensity and stability. The maleimide group allows for selective conjugation with thiol groups (-SH) in cysteine residues, making it a valuable tool for studying protein structure, dynamics, and interactions. It is also employed in fluorescence microscopy and flow cytometry to visualize and track cellular components in live or fixed cells. Additionally, it is used in Förster resonance energy transfer (FRET) studies to investigate molecular interactions and conformational changes. Its bright red fluorescence makes it suitable for multiplexing with other fluorophores in complex experimental setups.