Learn how to use this product pCSG-IBA103 is a large expression vector with universal features for the transient expression of target proteins with a C-terminal Twin-Strep-tag® and for the generation of stable mammalian cell lines. The vector carries an ampicillin resistance cassette for the selection of transformed E. coli cells and ColE1 origin for a high plasmid copy number. Extrachromosomal replication in mammalian cells could occur either by origin of replication from Epstein-Barr Virus (oriP) or SV40 ori. For origin of replication from oriP, the vector provides the EBNA-1 gene, and for the latter, the cell line has to be latently infected with SV40 or express the SV40 large T antigen, such as HEK293T, COS-1, COS-7. The neomycin resistance gene (NeoR) can select stable cell lines. In addition, the human cytomegalovirus (CMV) immediate-early promoter enables a high-level expression in a wide range of mammalian cells. Please note that cloning into pCSG-IBA acceptor vectors compulsorily requires the restriction enzyme Esp3I since no other MCS for the integration of a gene of interest is available. Besides the direct cloning of the gene of interest into pCSG-IBA vectors with Esp3I, another option via an Entry Vector is possible.