SNAP-tag is a mutant form of O6-alkylguanine-DNA alkyltransferase (a DNA repair protein) that can, when fused to proteins of interest, be used for specific labeling of cells. SNAP-tag reacts specifically and rapidly with benzylguanine (BG) which can be linked with a range of synthetic labels, including fluorophores. The labels transfer from BG derivatives to the SNAP-tag in an irreversible, covalent fashion, enabling fast and quantitative one-step labeling of the protein of interest with minimal off-target signal and low cellular toxicity.
These Rosa26SNAPCaaX cre reporter mice conditionally express SNAP-tag associated with a membrane-associated CaaX consensus sequence driven from the Gt(ROSA)26Sor promoter. Cre-mediated excision of a floxed stop cassette enables expression of membrane-associated SNAP-tag in the tissue(s) of interest and permits selective labeling upon application of a BG-linked compound.
Crosses with deleter and peripheral/central nervous-specific cre strains (e.g. NFH-cre, Avil-cre, Vglut2-cre) have demonstrated strong, sustained, cell-specific BG-fluorophore labeling capabilities. Labeling tolerates standard histological sample preparation and attains fluorescence intensities greater than those of more standard fluorescent protein reporters.
In addition for fluorophore labeling, applications may also include chromophore-assisted light activation (CALI) for ablation of cells, and the use of synthetic calcium or voltage sensors for neuronal activity imaging.
