Minute-size fractions achieved in two-dimensional electrophoresis, IEF, and PAGE with SDS and bands from electrophoresis of nucleic acids are detected differently than protein electrophoresis fractions. Labeled polypeptide probes are used to detect these proteins; labeled single-stranded nucleic acid fragments are used to detect nucleic acids. Each probe is made with a label designed to generate a detectable signal. The label is bound to a probe, and a system is created to visualize the signal when the probe is bound to the target.
The most common labels are radioactive isotopes and fluorescence dyes. Chemiluminescence and color or ultraviolet absorbance are also used.
