Methods using O6-alkylguanine-DNA alkyltransferases

A method using O6-alkylguanine-DNA alkyltransferases (AGT) is disclosed for transferring a label from a substrate to a fusion protein comprising the AGT. This allows the detection and/or manipulating of the fusion protein, both in vitro and in vivo, by attaching mols. to the fusion proteins that introduce a new phys. or chem. property to the fusion protein. Examples of such mols. are, among others, spectroscopic probes or reporter mols., affinity tags, mols. generating reactive radicals, cross-linkers, ligands mediating protein-protein interactions or mols. suitable for the immobilization of the fusion protein. A peptide-human AGT fusion protein was labeled in Escherichia coli using I. Biotinylated proteins were detected by Western blotting. [on SciFinder (R)]