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Protein Labeling

SNAP- and CLIP-tag™ protein labeling systems enable the specific, covalent attachment of virtually any molecule to a protein of interest. There are two steps to using this system: cloning and expression of the protein of interest as a SNAP-tag® fusion, and labeling of the fusion with the SNAP-tag substrate of choice. The SNAP-tag is a small protein based on human O6-alkylguanine-DNA-alkyltransferase (hAGT), a DNA repair protein. SNAP-tag substrates are dyes, fluorophores, biotin, or beads conjugated to guanine or chloropyrimidine leaving groups via a benzyl linker. In the labeling reaction, the substituted benzyl group of the substrate is covalently attached to the SNAP-tag. CLIP-tag is a modified version of SNAP-tag, engineered to react with benzylcytosine rather than benzylguanine derivatives. When used in conjunction with SNAP-tag, CLIP-tag enables the orthogonal and complementary labeling of two proteins simultaneously in the same cells. 

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

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FAQs for Protein Labeling

Protocols for Protein Labeling

Application Notes for Protein Labeling

Features

  • 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

Applications

  • 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.

Protein Labeling with ACP-tag

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

Videos

  1. fluorescent_COS7_thumb

    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.

  2. SNAPtag_Tutorial_thumb

    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.

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