pTV118N is a phagemid vector constructed from a modified pUC118. This plasmid contains the sequence CCATGG which includes the cleavage sequence for the restriction enzyme NcoI as well as the start codon (ATG) for lacZ. This enables target gene expression at the NcoI site. Protein expression is enabled by the vector's lac promoter. The pTV118N vector also contains a lacZ SD sequence. There are eight bases between the lacZ SD sequence and the initiation codon, allowing high level expression of target genes. Induction of single-stranded DNA by helper phage and its subsequent sequencing with RV-N primer enables accurate sequencing from the start codon site, ensuring an insert's correct translation frame.