pSNAPf Vector is a mammalian expression plasmid intended for the cloning and stable or transient expression of SNAP-tag protein fusions in mammalian cells. This plasmid encodes SNAPf, a SNAP-tag protein, which is expressed under control of the CMV promoter. The expression vector has an IRES (internal ribosome entry site) and a neomycin resistance gene downstream of the SNAPf for the efficient selection of stable transfectants. pSNAPf Vector contains two multiple cloning sites to allow cloning of the fusion partner as a fusion to the N- or C-terminus of the SNAPf. The SNAP-tag is a novel tool for protein research, allowing the specific, covalent attachment of virtually any molecule to a protein of interest. The SNAP-tag is a small protein based on mammalian O6-alkylguanine-DNA-alkyltransferase (AGT). SNAP-tag substrates are derivatives of benzyl purines and benzyl pyrimidines. In the labeling reaction, the substituted benzyl group of the substrate is covalently attached to the SNAP-tag.