The pHEK293 Ultra Expression Vectors are plasmids for transient overexpression of a protein of interest in human HEK 293 cells. Protein expression using these vectors can be up to 10 times higher than what is obtained from vectors with conventional cytomegalovirus (CMV)-derived promoters. Prior to purchasing these products, all customers must complete a purchaser"s agreement to submit with the order.

High protein expression is accomplished using the HIV-1 TAR-Tat system. The TAR (transactivation response) element is an RNA sequence derived from human immunodeficiency virus type 1 (HIV-1) that forms a stem-loop structure at the 5’ end of HIV-1 RNAs. Tat is an RNA-binding protein that activates transcription by binding to the TAR and promoting transcriptional elongation.

The pHEK293 Ultra Expression Vectors exploit this transcriptional activation mechanism; the TAR sequence is present in the 5" untranslated region of the target gene, and a Tat expression cassette is included either on the same vector (Cat. # 3390) or on a separate plasmid (Cat. # 3392). This system allows efficient expression of Tat protein, thereby greatly increasing the amount of target protein that is expressed. Since the TAR sequence is located in the untranslated region of the target gene, it does not affect the amino acid sequence of the expressed target protein.