CLONABLE TAG FOR PURIFICATION AND ELECTRON MICROSCOPY LABELING

摘要

The disclosure provides compositions and methods for heavy atom labeling of a target protein using a clonable tag. The clonable tag comprises a metallothionein or a fragment thereof, such as metallothionein, which may be fused to a target protein of interest. The tag permits the target protein to be labeled with a heavy atom, such as gold, silver, or mercury, and thus permits visualization of the target protein by electron microscopy. Also provided are methods for purification of a target protein using metallothionein, or a fragment thereof, as an affinity tag. The metallothionein fusion may be purified on immobilized metal affinity chromatography (IMAC) column charged with a metal such as cadmium.