CLIP-tag

CLIP-tag is a variant of the SNAP-tag. Both tags are novel self-labeling protein tags which combine specificity with covalent binding between the tag and its substrate. Both are 20kDa protein tags which are easily expressed in a variety of common expression systems. The CLIP-tag works well as either N-or C-terminal CLIP-tag fusion.

CLIP-tag cleaves para-substituted benzyl cytosines by transferring the substituted benzyl group to its active site and releasing free cytosine. The resulting thioether bond is highly stable. There are no obvious limitations to the nature of the chemical compound that can be linked to CLIP-tag. The self labeling reaction is highly specific, because benzyl cytosines are stable in biochemical conditions and no other protein reacts with this class of substance.

The primary application for the CLIP-tag is application simultaneous with the SNAP-tag for simultaneous dual protein labeling inside living cells. Further applications is the selective detection of fusion proteins on cell membranes and the direct detection of CLIP-tag fusion proteins in SDS-PAGE gels.

CLIP-tag (purple) fused to protein of interest (blue) self-labels with label X (green).

Literature:

Selected Publications
Gautier A. et al.:"An Engineered Protein Tag for Multiprotein Labeling in Living Cells". Chemistry & Biology 15, Feb 2008, pp. 128-136, DOI 10.1016/j.chembiol.2008.01.007
Keppler A. et al.: "Labeling of fusion proteins with synthetic fluorophores in live cells." PNAS 101 (2004), pp. 9955-9959.
Keppler A. et al.:"Labeling of fusion proteins of O(6)-alkylguanine-DNA alkyltransferase with small molecules in vitro and in vivo." Methods 32 (2004), pp. 437-444.
Huber W. et al.:"SPR-based interaction studies with small molecular weight ligands using hAGT fusion proteins." Analytical Biochemistry 333(2) (2004), pp280-288.
Jongsma M.A., Litjens R. H.:"Self-assembling protein arrays on DNA chips by auto-labeling fusion proteins with a single DNA address", Proteomics,
2006 Apr. 5

All Publications Application Notes