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ACP-tag and MCP-tag Systems

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ACP-tag and MCP-tag are small protein tags based on the acyl carrier protein. In contrast to SNAP-tag® and CLIP-tag™, which are self-labeling, the presence of an added synthase is required for the formation of a covalent link between the ACP-tag or MCP-tag and their substrates, which are derivatives of Coenzyme A. In the labeling reaction, the group conjugated to CoA is covalently attached to the ACP-tag or MCP-tag by a recombinant synthase. Labels can be covalently attached to a tag using either ACP-Synthase (NEB #P9301) for ACP-tag labeling or SFP-Synthase (NEB #P9302) for dual ACP- and MCP-tag labeling.


  • Small – Expressed tag is only 8 kDa (77aa) 
  • Versatile – ACP- and MCP-tagged fusions can be co-expressed and sequentially labeled for two color applications on cell surfaces 
  • Specific – Components remain exclusively extracellular, preventing intracellular labeling  
  • Precise – Label is covalently bound under biological conditions in a defined position 
  • Non-toxic – Substrates are non-toxic to living cells 
  • Selection – Choice of substrates available, including 488, 547, 647 and biotin
SNAP-tag® is a registered trademark of New England Biolabs, Inc.
CLIP-tag™ is a trademark of New England Biolabs, Inc.
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    Fluorescent Labeling of COS-7 Expressing SNAP-tag Fusion Proteins for Live Cell Imaging

    Watch as Chris Provost, of New England Biolabs, performs fluorescent imaging of live COS-7 cells expressing SNAP-tag® fusion proteins.

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    SNAP-tag Overview Tutorial

    View an interactive tutorial explaining the mechanism of our SNAP-tag® technologies and reagents available for researchers wishing to study the function and localization of proteins in live or fixed cells.