Selective cross-linking of interacting proteins using self-labeling tags

J Am Chem Soc. 2009 Dec 16;131(49):17954-62. doi: 10.1021/ja907818q.


We have designed molecules that permit the selective cross-linking (S-CROSS) of interacting proteins in cell lysates and the sensitive detection of the trapped complexes through in-gel fluorescence scanning. S-CROSS requires the expression of the putative interacting proteins as fusion to CLIP-tag or SNAP-tag, two protein tags that can be specifically labeled with synthetic probes. Bifunctional molecules that contain the substrates of the two tags connected via a fluorophore are used to selectively cross-link interacting proteins in cell lysate. The amount of trapped complex can be then quantified after SDS gel electrophoresis by in-gel fluorescence scanning. On the basis of a detailed kinetic analysis of the cross-linking reaction, we showed that the cross-linking efficiency can be used as an indicator of interaction between two proteins, allowing thereby the unambiguous identification of interacting protein pairs. We validated our approach by confirming a number of interactions through selective cross-linking and showed that it permits the quantitative and simultaneous analysis of multiple homotypic and heterotypic protein complexes and the differentiation between strong and weak protein-protein interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cross-Linking Reagents / chemistry*
  • Electrophoresis, Polyacrylamide Gel
  • Microscopy, Fluorescence
  • Protein Binding
  • Proteins / chemistry*
  • Sodium Dodecyl Sulfate / chemistry
  • Staining and Labeling


  • Cross-Linking Reagents
  • Proteins
  • Sodium Dodecyl Sulfate