Grey Fox Lung Cells with mTag-GFP2 and Paxillin
The FoLu line was established from the lung tissue of an adult female grey fox (Urocyon cinereoargenteus). The cells are susceptible to vesicular stomatitis, herpes simplex, and vaccinia viruses, but are resistant to poliovirus. FoLu cells are negative for reverse transcriptase, indicating the lack of integral retrovirus genomes.
When paxillin was first found in cells, it was recognized as a protein that contained phosphotyrosine and that could be transformed by src, the first oncogene ever discovered. Later studies revealed that paxillin is concentrated at the close points of contact between cells and the surrounding matrix known as focal adhesions. There the protein functions in cell motility and spreading. More recently researchers have found that paxillin also appears to behave as an adaptor protein involved in directing signal transmission downstream.
Focal adhesions were fluorescently tagged in the fox lung fibroblasts (FoLu line) featured in the digital video in this section with mTagGFP2 fused to paxillin. mTagGFP2 is a bright green monomeric variant of TagGFP, which was produced from the mutation of the Aequorea macrodactyla fluorescent protein similar to GFP. mTagGFP2 exhibits improved photostability and performs better than its parent protein in fusions. Peak excitation and emission of mTagGFP2 occur at 483 and 506 nanometers, respectively.