pCMS-EGFP is a mammalian expression vector that allows you to express your gene of interest at high levels by cloning it into a multiple cloning site (MCS) downstream of the immediate early promoter of cytomegalovirus (PCMV IE). The intervening sequence (IVS) between PCMV IE and the MCS is an intron that is efficiently spliced out following transcription. SV40 polyadenylation signals downstream of the MCS direct proper processing of the 3' end of the mRNA from your gene of interest. Bacteriophage T7 and T3 promoters are located upstream and downstream of the MCS, respectively.

pCMS-EGFP uses the enhanced green flourescent protein (EGFP) as a transformation marker. EGFP is a red-shifted variant of wild-type GFP from Aquorea victoria (1–3). EGFP has been optimized for brighter fluorescence and higher expression in mammalian cells. (Excitation maximum = 488 nm; emission maximum = 507 nm.) EGFP encodes the GFPmut1 variant (4) which contains the double-amino-acid substitution of Phe-64 to Leu and Ser-65 to Thr. The coding sequence of the EGFP gene contains more than 190 silent base changes which correspond to human codon-usage preferences (5). Sequences flanking EGFP have been converted to a Kozak consensus translation initiation site (6) to further increase the translation efficiency in eukaryotic cells. EGFP is expressed from the SV40 enhancer/promoter, and a polyadenylation signal from the bovine growth hormone (BGH) gene directs proper processing of the 3' end of the EGFP mRNA. The SV40 origin also allows for replication in mammalian cells expressing the SV40 T antigen.The vector backbone also contains the β-lactamase gene for ampicillin resistance and a ColE1 origin of replication for propagation in E. coli and an f1 origin for single-stranded DNA production.

The name of the vector comes from the order of four critical elements: the CMV IE promoter; the MCS; the SV40 promoter; and EGFP.

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Genes cloned into the MCS must contain an ATG start codon. pCMS-EGFP and derivatives can be introduced into mammalian cells by any standard method. Transfected cells can be monitored and/or selected by flow cytometry based on the fluorescence of EGFP. Sense or antisense RNA can be transcribed from the T7 and T3 promoters, respectively.