Tag/Loading Control Antibodies

Useful resources

What is a Tag Antibody? What are Tag Antibodies used for?

A tag, or an epitope tag, is an antigenic sequence such as a protein or a polyhistidine that is determinant for the binding of a special antibody, which determines the specificity of an antigen. The tag is usually added to a protein of interest by using genetic engineering, forming a fusion protein which is detected by a corresponding antibody. Antibodies that specially recognize and bind these tag epitopes are called epitope Tag antibodies or Tag antibodies. When no specific antibodies are available in the detection of protein of interest, tag antibodiees are alternative and needed. Tag antibodies are used for protein isolation and purification, the tracking of protein expression and localization, protein-protein interactions. Some common experiments such as ELISA, western blotting, immunofluorescence and immunoprecipitation often use different tag antibodies. More details of tag antibodies, please read this article: Tag Antibodies, Your Good Partner in Protein Research.

What is a Loading Control Antibody? What are Loading Control Antibodies used for?

Control antibodies, as the name means, are series of internal control antibodies. They specific for a highly and constitutively expressed protein. Generally, control antibody can be divided into two groups, including isotype control antibodies and loading control antibodies. The best loading control antibody should be constantly and stably expressed in different tissues and under different physiological and pathological conditions. Housekeeping proteins are typically ideal candidates of loading control antibodies. Loading control antibodies are necessary to obtain accurate expression data in the western blotting. They are responsible for monitoring target proteins in the western blotting, confirming equal sample loading and gel-to-membrane transfer that causes more intense staining at the edge of the blot, and guarding against the "edge effect" in order to normalize results. Loading control antibodies can be also used to detect whether protein loading variation has occurred and may interpret observed variations in the target band(s).

So it is important to know How to select right Loading Control Antibodies for your WB.