pETBlue2 has a number of restriction sites between nucleotid

pETBlue-2 has a number of restriction sites between nucleotides 276 and 464, why is that?

Image: https://www.chemie.uni-kl.de/fileadmin/agpierik/Methoden/pETBlue-2.pdf

Solution

In the given vector multiple cloning region 276–467 (Nco I–Pac I) is present because if cloning of any DNA sequnce has to be done in the vector it will be inserted in the multiple cloning site and it is specifically present in between the LAC Z site because if the DNA is inserted in between in LACZ site then the LACZ site will get disrupt and the recombinat plasmid will not produce blue colonies in the presence of X gal which produces blue color in the presence of -galactosidase, a gene product of LACz. DNA ligated into the plasmid disrupts the peptide and therefore the complementation process, and no functional -galactosidase can form. By using this vector we can select the recombinant plasmids by doing blue white screening in the presence of X gal in the selection media.