Fluorescent Subcellular Localisation Vectors and Reporter Gene Assays

Track subcellular structures and quantify gene activity with matched reporter tools

Two questions come up constantly in cell biology. Where does a protein sit inside the cell, and how strongly does a gene switch on. Subcellular localisation vectors answer the first for you, and reporter gene assays answer the second.

Cyto-Tracer vectors fuse copGFP to an organelle-specific signal peptide, marking a single compartment, organelle, vesicle, or structure in your living cells. The constructs work in transient transfection, and they package into virus to build a stable tracer line in primary, tumour, or stem cells. The MSCV promoter suits stem and haematopoietic cells, and CMV covers the easier cell types you work with.

copGFP comes from the copepod Pontellina sp., with human-optimised codons for strong expression. It is monomeric, non-toxic, and non-aggregating, and it stays stable from pH 4 to pH 12 with no added cofactors. Brightness runs about 1.3 times that of EGFP, with excitation at 482 nm and emission at 502 nm. An untagged GFP vector is available when you want to fuse your own tag.

Reporter gene assays turn promoter and pathway activity into a signal you can measure. Secrete-Pair kits detect GLuc alone, or GLuc paired with SEAP for a dual read. Both reporters are secreted, so you sample live cultures without lysing cells. Luc-Pair kits cover firefly and Renilla luciferase, singly or as a duo, in three formats. The HT (High Throughput) and 2.0 kits hold the signal stable over time, so sample-to-sample variation from signal decay stays low when you assay a large number of samples. The HS (High Sensitivity) kits give maximal signal intensity instead, with the trade-off that the signal decays faster under normal laboratory conditions, which suits smaller batches unless sample injectors are used.

Choosing the right fluorescent or reporter system

1. You want to watch an organelle or structure move in live cells. A Cyto-Tracer copGFP fusion vector targeted to that compartment images directly in your cells, with no chemical stain needed.
2. You need a stable, heritable tracer line. Cyto-Tracer constructs package into lentivirus, giving a selectable copGFP line in the cell type you work with, including stem and primary cells.
3. You are transfecting stem or haematopoietic cells. The MSCV promoter construct is the better fit for those cells. CMV covers other, easier-to-transfect types.
4. You need to measure promoter or pathway activity without lysing cells. Secrete-Pair GLuc and GLuc/SEAP kits let you sample your medium directly at each time point.
5. You are running a large batch of luciferase assays. HT (High Throughput) and 2.0 kits hold signal stable across many samples. HS (High Sensitivity) kits give maximal signal from a small batch.