A polyhistidine-tag is an amino acid motif in proteins that consists of at least five histidine (His) residues, often at the N- or C-terminus of the protein. The tag was invented by Roche. His-tags are useful in a wide variety of processes including protein purification and binding assays. Synonyms: Monoclonal His Tag antibody, Anti-His Tag antibody, 6XHis antibody, Polyhistidine Tag antibody, HIS6 Tag antibody, 6-His antibody, HHHHHH antibody.