Assembled through the combination of three DNA fragments: i) a 1974bp fragment covering the mh upstream regulatory sequences; ii) a 149bp fragment containing the Tag:V5 tag sequence fused in frame to some mh coding sequence; iii) a 2341bp genomic fragment covering the rest of the mh coding sequence and 1531bp downstream of the stop codon excised from the CH322S124H21 BAC using SacII and XbaI. The wild type HEMIH sequence in the SprT domain has been mutated to HVMIH.