The pET-45b(+) vector carries an N-terminal His?Tag® coding sequence followed by an enterokinase cleavage site and an optional C-terminal S?TagTM sequence. Unique sites are shown on the circle map. Note that the sequence is numbered by the pBR322 convention, so the T7 expression region is reversed on the vector map. The f1 origin is oriented so that infection with helper phage will produce virions containing single-stranded DNA that corresponds to the coding strand. Therefore, single-stranded sequencing should be performed using the T7 Terminator Primer (Cat. No. 69337-3).