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ACP/MCP Surface

The ACP-tag and MCP-tag protein labeling technologies are based on an enzyme-catalysed post-translational modification.  Recombinant target protein that is fused to an acyl carrier protein (ACP), is labeled specifically with CoA derivatives, catalyzed by the phosphopantetheinyl transferase ACP Synthase (1).  The ACP-tag is small, only 8 kDa (2).  MCP-tag, a mutant of ACP-tag, is labeled by the phosphopantetheinyl transferase SFP Synthase but not by ACP Synthase, thereby permitting selective simultaneous labeling in a sample.

Membrane proteins are challenging to study given their hydrophobic nature, generally low native abundance and intrinsic instability (3,4).  Regardless, half of all protein drug targets are membrane proteins.  For imaging, most fluorescent proteins (i.e. GFP) cannot specifically visualize cell surface subpopulations.  However, the ACP-tag/MCP-tag system is a cell surface-specific system since all of its substrates are non-cell permeable.  It can specifically label subpopulations of target protein expressed on cell surface using non-cell permeable substrates (5).  This approach permits discrimination of different populations of a cell surface protein: those properly translocated to the plasma membrane from those retained in the secretory pathway or already internalized (e.g. upon ligand binding).  


  1. George, N., Pick, H., Vogel, H. et al. (2004) J. Am. Chem. Soc. 126, 8896. PMID: 15264811
  2. Yin, J., Straight, P.D., McLoughlin, S.M. et al. (2005) Proc. Natl. Acad. Sci. USA 102, 15815. PMID: 16236721
  3. Lacapère J-J, Pebay-Peyroula E, Neumann J-M, Etchebest C. (2007) Trends Biochem Sci. 32, 259–270. PMID: 17481903
  4. von Heijne G. (2007) J Intern Med. 261, 543–557. PMID: 17547710
  5. Keppler, A., Pick, H., Arrivoli, C. et al. (2004) Proc. Natl. Acad. Sci. USA 101, 9955. PMID: 15226507

SNAP-tag® is a registered trademark of New England Biolabs, Inc.

FAQs for ACP/MCP Surface

Protocols for ACP/MCP Surface


  • Simultaneous dual protein labeling on the surface of live cells
  • Protein localization and translocation
  • Pulse-chase experiments
  • Receptor internalization studies
  • Selective cell surface labeling
  • Protein detection in SDS-PAGE
  • Flow cytometry
  • High throughput binding assays in microtiter plates
  • Biosensor interaction experiments
  • FRET-based binding assays
  • Single molecule labeling
  • Super-resolution microscopy

Protein Labeling with ACP-tag

ACP-tag (red) fused to the protein of interest (blue) is labeled in the presence of a required synthase.

SNAP-tag®, CLIP-tag™ and ACP/MCP-tag Substrate Selection Chart

NEB offers a large selection of fluorescent labels (substrates) for SNAP-, CLIP-, ACP- and MCP-tag fusion proteins.

Legal Information

This product is covered by one or more patents, trademarks and/or copyrights owned or controlled by New England Biolabs, Inc (NEB).

While NEB develops and validates its products for various applications, the use of this product may require the buyer to obtain additional third party intellectual property rights for certain applications.

For more information about commercial rights, please contact NEB's Global Business Development team at

This product is intended for research purposes only. This product is not intended to be used for therapeutic or diagnostic purposes in humans or animals.

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