pBluescript II phagemids, such as pBluescript II SK, are cloning vectors designed

  • to simplify commonly used cloning and sequencing procedures
  • construct nested deletions for DNA sequencing
  • generate RNA transcripts in vitro and site-specific mutagenesis
  • gene mapping

pBluescript II (+) and (–) are available with two polylinker orientations designated as either KS or SK using the following convention:

  • in the KS orientation, the Kpn I restriction site is nearest to lacZ promoter and the Sac I restriction site is farthest from the lacZ promoter
  • in the SK orientation, the Sac I site is the closest restriction site to the lacZ promoter and the Kpn I site is the farthest.

They have following properties:

  • These are 2961bp plasmid, derived by replacing pUC19 polylinker of pBS (+/-) with synthetic polylinker.
  • SK designation indicates that the polylinker is oriented such that the lacZ transcription proceeds from Sac I to Kpn I.
  • 21 unique restriction sites in the multiple cloning regions.
  • Total of 131 amino acids of β-galactosidase coding sequence are present.
  • Blue/White color selection.
  • pBS has a T3 promoter on one end side and a T7 promoter on the other terminal end. This is key because it enables one to isolate the double-stranded phagemid DNA and transcribe it in vitro with either of these two phage polymerases to produce pure RNA transcripts to coincide with either of the two different strands.
  • In vitro RNA transcription with T3 or T7 RNA polymerase and are capable of double and single-stranded sequencing.
Figure 15. Map of pBluescript II SK
Figure 15. Map of pBluescript II SK