SNAP Companion

The non-overlapping substrate specificity of SNAP-tag® and CLIP-tag™ enables the orthogonal and complementary labeling of two proteins simultaneously in the same cell. Furthermore, SNAP-tag and CLIP-tag based pulse-chase experiments allow for visualization of different generations of proteins and analysis of protein turnover in living cells (1-3). Additionally, there are a numbers of companion products designed to enable a wide variety of other applications including: Biotin substrates, SDS-PAGE specific SNAP-tag and CLIP-Vista labels, non-fluorescent blocking agents, resin and magnetic beads for pull-down applications, building blocks for the generation of custom substrates, and a SNAP-tag specific purified protein and antibody.


  1. Jansen, L. et al (2007) J.Cell. Biol. 176, 795-805. PMID: 17339380
  2. Farr, G.A. (2009) J. Cell. Biol. 186, 269-282. PMID: 19620635
  3. Milenkovic, L. (2010) J. Cell. Biol. 187, 365-374. PMID: 19948480

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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FAQs for SNAP Companion

Protocols for SNAP Companion

Application Notes SNAP Companion


  • Clone and express once, then use with a variety of substrates
  • Non-toxic to living cells
  • Wide selection of fluorescent substrates
  • Highly specific covalent labeling
  • Simultaneous dual labeling


  • Simultaneous dual protein labeling inside live cells
  • Protein localization and translocation
  • Pulse-chase experiments
  • Receptor internalization studies
  • Selective cell surface labeling
  • Protein pull-down assays
  • 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 SNAP-tag and CLIP-tag

The SNAP- (gold) or CLIP-tag (purple) is fused to the protein of interest (blue). Labeling occurs through covalent attachment to the tag, releasing either a guanine or a cytosine moiety.

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.