The prospects of fluorescence microscopy changed dramatically with the discovery of fluorescent proteins in the 1950s. The starting point was the detection of the jellyfish Aequorea victoria green fluorescent protein (GFP) by Osamo Shimomura. Hundreds of GFP mutants later, the range of fluorescent proteins reaches from the blue to the red spectrum.
There are a lot of light-emitting processes occurring in nature. Luminescence is an umbrella term for those kinds of events where light emission is not the result of high temperatures. This article depicts the different forms of luminescences and goes into detail in the case of fluorescence. Relevant technical terms describing a fluorochrome, like quenching, bleaching or quantum yield, are explained in the second part of the article to give detailed insights into basic characteristics of fluorescent molecules.
Due to their special role in organ function and the exchange of biological components some body cells developed certain polarization characteristics. These are reflected in differences of their plasma membrane composition. The essential and fascinating task of polarized protein transport in epithelial cells is to get the right protein into the right membrane.
Fluorescent proteins are the fundament of recent fluorescence microscopy and its modern applications. Their discovery and consequent development was one of the most exciting innovations for life sciences in the last century and the starting point of the deciphering of numberless natural phenomena.
Application of TIRF microscopy (Total Internal Reflection Fluorescence) allows the visualization of structures at the apical surface of polarized epithelial cells that have been hidden in conventional fluorescence microscopy images. Hence, the approach reveals new insights into the composition of this characteristic cell pole that elucidate processes in apical protein trafficking.