Absolute multiplexed protein quantification using QconCAT technology.

In addition to protein identification, protein quantification is becoming a key output of proteomic experiments. Although relative quantification techniques are more commonplace and central to discovery proteomics, most assays require absolute quantification. The growth in systems biology has also increased the demand for absolute protein abundance values for input into models. QconCATs are created by concatenating peptide sequences taken from the target proteins into artificial proteins. The QconCAT acts as a source of internal standards and enables parallel absolute quantification of multiple proteins. QconCATs are typically applied in targeted proteomic workflows and so benefit from the greater sensitivity and wider dynamic range of these approaches. In this chapter, we discuss the design, construction, expression, and deployment of a QconCAT and the resulting experiments required for multiplex absolute quantification.