PBluescript

In genetics, pBluescript (pBS) or pBluescript II is a commercially available phagemid containing several useful sequences for use in cloning with bacteriophage. The sequences include a polylinker sequence, antibiotic resistance sequence and an E. coli and f1 helper phage origin of replication. The polylinker sequence is located within a LacZ controlled gene designed to provide a blue coloration when expressed in bacteria. If the gene is disrupted by successful insertion of a DNA sequence into to gene, the bacteria exhibit a white coloration in Blue white screening, distinguishing successful recombination from those phagemids which were not altered.

The pBluescript cloning system is a product of Stratagene.