6x-His tags are a type of tag for expressed proteins. This tag is made up of 6 histidine residues attached to either the N- or C-terminal of a protein. Proteins expressed with this type of tag are then traditionally purified using a divalent metal ion column. However, using an antibody specific to this 6x-His tag, the protein can be analyzed for by Western blot or immunofluorescence techniques, thus eliminating the need for a protein-specific antibody. 6x-His tags are particularly effective for the purification of protein expressed in E. coli systems.Synonyms: 6xHis-Tag, HHHHHH Tag, HIS6 Tag, His Tag