Chad Zimprich1, Natasha Karassina1, Randy Learish1, Soshana Behrstock1, Nidhi Nath1, Aldis Darzins1, Marjeta Urh1, Keith V. Wood1, Georgyi V. Los1, Mark McDougall2 and Dieter Klaubert2
1Promega Corporation, 2800 Woods Hollow Rd, Madison, WI 53711
2Promega Biosciences, Inc., 277 Granada Drive, San Luis Obispo, CA 93401
The HaloTag® Interchangeable Labeling Technology is a novel tool for (1) imaging live or fixed mammalian cells that express the HaloTag® Protein or protein fusions, (2) analyzing post-translational modification of labeled proteins, and (3) capturing and immobilizing protein fusions and protein complexes generated in living cells or in vitro. The technology is based on the efficient formation of a covalent bond between an engineered reporting protein and its specific ligand, either in living cells, in solution, or on a solid support. The reporter protein is a genetically engineered derivative of a catalytically inactive hydrolase designed to form a stable, covalent bond to synthetic ligands. The ligands are small chemical tags capable of carrying a variety of functionalities, such as fluorescent labels, environmental sensors, affinity handles, or attachments to a solid phase. The covalent bond forms rapidly under general physiological conditions, is highly specific, and essentially irreversible. The open architecture of the technology ensures interchangeability of ligands, thereby facilitating a variety of functional studies (including imaging at different wavelengths and temporal or spatial separation of protein pools) without requiring changes to the underlying genetic construct. The HaloTag® Technology complements existing methods and provides new options for cellular analysis and protein immobilization.