Plasmid #3 serves as a template for tagging target proteins with N-terminal CL7 tag. It has three options for the 5’ placement of target genes (see cloning options below), and XhoI is the 3’ cloning site. All three options require a stop codon encoded in the 3’ cloning primer. There is an existing 1711 base pair restriction fragment inserted at the HindIII/XhoI restriction sites.