2017 Volume 68 Issue 1 Pages 44-51
We analyzed transient and stable eukaryotic gene expression using internal ribosome entry site (IRES) and green fluorescent protein (GFP)-S65T (IRES-GFP) expression systems. The IRES-containing vector enables simple construction of a plasmid and easy detection of transfected cells, as well as an estimation of the levels of the gene of interest. This system is useful for measuring changes in the intracellular calcium concentration using the fluorescent calcium indicator Fura-2 AM, although subcellular localization of the protein of interest is not detectable. Importantly, the IRES-GFP plasmid showed delayed expression and an approximate 40% reduction in fluorescence intensity, which suggests that usage of IRES-containing expression system might cause under-estimation of desired gene. Although this technique has some disadvantages, the IRES-containing vector is simple and straightforward for gene expression analysis, comparing with co-expression procedure of multiple plasmids.
