MS Bioworks LLC 1 article published in JoVE Biology Discovering Protein Interactions and Characterizing Protein Function Using HaloTag Technology Danette L. Daniels1, Jacqui Méndez1, Hélène Benink1, Andrew Niles1, Nancy Murphy1, Michael Ford2, Richard Jones2, Ravi Amunugama2, David Allen2, Marjeta Urh1 1Promega Corporation, 2MS Bioworks LLC HaloTag technology is a multifunctional technology which has shown significant success in isolation of both small and large protein complexes from mammalian cells. Here we highlight the advantages of this technology compared to existing alternatives and demonstrate its utility to study numerous aspects of protein function inside eukaryotic cells.