Sidebar: Tagging to Capture Interaction
In order to measure its interaction with other proteins, it is often necessary to genetically fuse a protein of interest with a detectable molecule that acts as a tag; many such tagging technologies are available to the life science community. Promega has introduced a new application of HaloTag technology for isolation and localization studies of intracellular macromolecular complexes, including the ribosome and RNA polymerase, which have proven difficult to study using a single fusion tag.
Danette Daniels Hartzell, Ph.D., senior research scientist at Promega, presented data at the Gordon meeting using the technology that showed successful isolation of the large complexes, identified interacting proteins, demonstrated functionality, and analyzed localization in live cells using manual or automated imaging techniques.
“Often, in order to study protein interactions you need to use a variety of protein affinity or fusion tags,” said Dr. Hartzell. “The HaloTag technology allows researchers to have multifaceted protein analysis with a single protein tag.” The HaloTag protein has been evolved to covalently and rapidly bind its ligands, which include immobilization surfaces and fluorescent dyes, enabling users to either visualize or isolate complexes within a matter of 1–2 hours, according to Dr. Hartzell.
“In addition, due to the covalent capture aspect of the technology, complexes from even a very dilute solution are isolated, without the loss due to diffusion, which is commonly associated with other affinity tags.”