In standard Western blot (WB) approaches, denatured protein samples are separated according to their molecular weight with SDS-PAGE (polyacrylamide gel electrophoresis) and transferred to a membrane. The analysis of different organs, cell-types, and subcellular fractions like membranes, versus cytosol or different organelles may also provide useful information about differential protein expression levels. Enhanced chemiluminescent (ECL) detection systems are very sensitive, but have a narrow linear detection range that can be used for protein quantification. In general, the experiment has to be carefully optimized for reliable results.
Important: Some proteins have special requirements for good separation (e.g. unboiled samples or special gel systems). Please refer to the remarks sections for western blotting on the respective data sheet.
Separate the protein sample to be examined and a molecular weight standard using SDS-PAGE and transfer to a nitrocellulose membrane by electro-blotting. Follow the manufacturer's instructions for your SDS-PAGE and blotting device.
A very weak signal may be caused by the primary and/or secondary antibody concentration being too high. The ECL substrate solution has a limited capacity, and high amounts of local peroxidase can use up all the substrate within seconds before the picture is taken in your ECL reader.
Please try a lower concentration of primary and secondary antibodies in this case.
Note: The SYSY standard protocol generates good results in the SYSY labs and may be used as a reference. However, to achieve the highest specific signal and lowest non-specific background signal, the best antibody concentration, incubation temperature, and incubation time must be determined individually.