It is possible to co-express two or more proteins from the same vector. There are two possible strategies:
- The proteins are expressed under the regulation of different promoters. In this case, the genes are cloned sequentially into a vector containing different multiple cloning sites, e.g. pFastBac DUAL (Life Technologies), a baculovirus expression vector (see figure below).
- The proteins are cloned under the regulation of one promoter. In this case, the genes are cloned into a normal expression vector containing one promoter and one multiple cloning site (di- or multi-cistronic cloning). Each gene should have its own Shine-Dalgarno sequence and start codon.
For the dicistronic cloning into a pET vector, we have developed the procedure shown in the following cartoon. This procedure can be extended for multi-cistronic cloning.
The order in which the genes are cloned into the vector can be important for the expression levels of the different proteins.