BC-NH2 is an amine-terminated building block for the one-step synthesis of CLIP-tag™ substrates from NHS esters or other activated carboxylic esters of labels or surfaces. This building block allows you to make custom CLIP-tag substrates for labeling CLIP-tag fusion proteins. The BC-NH2 is particularly useful for the synthesis of fluorescent CLIP-tag substrates.
The CLIP-tag protein labeling system enables the specific, covalent attachment of virtually any molecule to a protein of interest. CLIP-tag is a protein tag based on human O6-alkylguanine-DNA-alkyltransferase (hAGT). CLIP-tag substrates are derivatives of benzylcytosine (BC). In the labeling reaction, the substituted benzyl group of the substrate is covalently attached to the reactive cysteine of CLIP-tag forming a stable thioether bond. Although CLIP-tag is based on the same protein as SNAP-tag®, the benzylcytosine substrates form a separate class of substrates, different from the benzylguanine substrates recognized by SNAP-tag. CLIP-tag and SNAP-tag can be used for orthogonal and complementary labeling of two proteins simultaneously in the same cells.
There are two steps to using this system: sub-cloning and expression of the protein of interest as a CLIP-tag fusion, and labeling of the fusion with the CLIP-tag substrate of choice. Expression of CLIP-tag fusion proteins is described in the documentation supplied with CLIP-tag plasmids. The labeling of the fusion proteins with the CLIP-tag substrate is described in this document.