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Updated: Jun 21, 2026

Cell-Type Specific Protein Purification and Identification from Complex Tissues Using a Mutant Methionine tRNA Synthetase Mouse Line
Published on: April 13, 2022
Site-specific N- and C-terminal labeling of a single polypeptide using sortases of different specificity
John M Antos1, Guo-Liang Chew, Carla P Guimaraes
1Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, Massachusetts 02142, USA.
Abstract:
The unique reactivity of two sortase enzymes, SrtA(staph) from Staphylococcus aureus and SrtA(strep) from Streptococcus pyogenes, is exploited for site-specific labeling of a single polypeptide with different labels at its N and C termini. SrtA(strep) is used to label the protein's C terminus at an LPXTG site with a fluorescently labeled dialanine nucleophile. Selective N-terminal labeling of proteins containing N-terminal glycine residues is achieved using SrtA(staph) and LPXT derivatives. The generality of N-terminal labeling with SrtA(staph) is demonstrated by near-quantitative labeling of multiple protein substrates with excellent site specificity.
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