WideScreen™ EpiTag™ Assay Overview  The Novagen® WideScreen™ Group has developed immuno-assay panels using a novel, powerful assay platform for the multiplex quantitation of phosphorylated proteins. WideScreen EpiTag™ assays for the bead-based xMAP® platform utilize EpiTag™ Technology licensed from Epitome Biosystems INC., which detects protein- and phosphoprotein-fragments rather than the traditional detection of intact proteins. Protein fragments are released by digestion with site-specific proteases. Antibody pairs are generated to unique amino acid sequences, or EpiTag™ Sequences, on these fragments. This approach provides a high degree of specificity and the ability to multiplex assays for a protein’s total and phosphorylated levels without cross-reactivity. In addition, the assay can accurately measure concentrations of phosphorylated target proteins as synthetic phosphopeptides are used to generate standard curves. EpiTag™ xMAP® Assay 
Cells or tissues are lysed and the extracted proteins are digested with a specific protease to release proteolytic fragments. The digested lysate is then used in a standard-format xMAP® Assay. A single sample preparation procedure is used for all WideScreen™ EpiTag™ Assays, removing the guesswork out of choosing a lysis buffer. The digested lysates are stable and can be frozen and thawed several times without significant loss of signal, providing an unparalleled degree of workflow flexibility. Targeting different fragments from the same protein allows both total and phospho-assays to be run together. This is a significant advantage over current assays where total- and phospho-assays cannot be multiplexed and are run in separate wells. The use of synthetic peptides and phosphopeptides as standards to generate standard curves allows direct comparisons of total- and phosphoprotein-concentrations in cell lysates. | 
