Fig. 1.

Principles of MTeC. (A) An MTeC bait plasmid is composed of an affinity tag fused in tandem with a peptide sequence possessing an amino acid to be posttranslationally modified in vivo followed by the catalytic domain of an enzyme known to modify the residue. (B) The MTeC bait plasmids are expressed in the cells of choice and, after the MTeC bait fusion protein is confirmed to be properly modified in vivo, the PTMBPs are biochemically purified. After SDS/PAGE of the purified material, visible protein bands can be isolated and identified by MS, or alternatively, complete sample mixtures can be submitted for protein identification. MTeC can also be used to verify and characterize PTM-dependent binding in vivo.