Molecular imaging is a science which gathered pace from early 21st century because of the burning need to evaluate molecular processes and cellular biology in living organisms and cellular structures without altering their physiological or biological structure. In this imaging technique, biomarkers are being used to recognize specific processes or pathways within the cell in relation to a designated biochemical reaction. The biomarkers will be able to react with the process under study and help them be visualized through special visualization techniques. Fluorescent protein tags are one such biomarker used for molecular imaging and have become invaluable in understanding the cellular processes which could explain disease states, drug reactions as well as immunological phenomena.
What are protein tags?
Proteins tags are peptide sequences which are genetically incorporated into a certain protein through various means. Once incorporated, these peptide sequences can be used for many different purposes and one such purpose is to visualize the attached protein. Thus, by designating a peptide sequence which can act as a fluorescent tag and incorporating it into a recognized protein this will allow fluorescent microscopy to be used to visualize and track the said protein.
What is the commonly used fluorescent protein tag in scientific research?
The discovery of the bioluminescent protein in 1961 from Aequorea Victoria jelly fish, marked the beginning of the evolutionary process of fluorescent protein tags and during that discovery the detection of a second protein, which can emit a green fluorescence when exposed to ultraviolet light, later became popular as the ‘green fluorescent protein’ (GFP). Later on, the gene which codes for the GFP was discovered and in the late nineties it was successfully used to track gene expression in bacteria and nematodes.
From its humble beginnings, the GFP has evolved a long-way at present and the scientists have been able to develop mutant variations of GFP in relation to its color, fusion as well as to act as biosensors. All these variations together are recognized as ‘fluorescent proteins’.
Furthermore, there have been new discoveries in which novel florescent proteins have been unearthed from various other species, which adds to the existing color spectrum of GFP and its mutants.
What are the visualizing modalities of fluorescent protein tags?
The effectiveness of fluorescent protein tags in relation to biological processes of a living cell could not have materialized, if visualizing modalities did not evolve to supplement the utilization of the protein tags. Thus, fluorescent microscopy have also evolved in the past decade and with the advent of widefield fluorescence and conefocal microscopy along with ultrafast low light level digital cameras and multi-tracking laser control systems, the future of fluorescent protein tags and its use have never been filled with potential.