Plasmid vectors for the expression of coding regions of eukaryotic genes in bacterial, insect and mammalian hosts are in common usage, such expression vectors are frequently used to encode hybrid fusion proteins consisting of a eukaryotic target protein and a specialized region designed to aid in the purification and visualization of the target protein. A system that has proven to be very successful relies on the insertion of a six histidine (6xHis) sequence in the N-terminus of the encoded protein, allowing for efficient coupling to Ni -chelating resins and purification by single step affinity chromatography. Visualization of such fusion proteins can be achieved by utilizing antibodies generated against specific peptide sequences downstream from the multiple cloning site. The antibody is useful for detection, isolation and localization of the His-tag proteins.Synonyms: 6xHis-Tag, HHHHHH Tag, HIS6 Tag, His Tag