Complex‐centric proteome profiling by SEC‐SWATH‐MS

Proteins are major effectors and regulators of biological processes that can elicit multiple functions depending on their interaction with other proteins. The organization of proteins into macromolecular complexes and their quantitative distribution across these complexes is, therefore, of great biological and clinical significance. In this paper, we describe an integrated experimental and computational technique to quantify hundreds of protein complexes in a single operation. The method consists of size exclusion chromatography (SEC) to fractionate native protein complexes, SWATH/DIA mass spectrometry to precisely quantify the proteins in each SEC fraction, and the computational framework CCprofiler to detect and quantify protein complexes by error‐controlled, complex‐centric analysis using prior information from generic protein interaction maps. Our analysis of the HEK293 cell line proteome delineates 462 complexes composed of 2,127 protein subunits. The technique identifies novel sub‐complexes and assembly intermediates of central regulatory complexes while assessing the quantitative subunit distribution across them. We make the toolset CCprofiler freely accessible and provide a web platform, SECexplorer , for custom exploration of the HEK293 proteome modularity. Synopsis The study presents an integrated framework for targeted, complex‐centric analysis based on size exclusion chromatography (SEC) and SWATH/DIA mass spectrometry. The workflow facilitates the parallel detection of hundreds of protein complexes and their variants at high selectivity and under error‐control. The presented workflow is based on the concept of complex‐centric proteome profiling and combines size exclusion chromatography (SEC) with SWATH/DIA mass spectrometry. The implementation of the complex‐centric data analysis is supported by the computational framework CCprofiler . Application of the SEC‐SWATH‐MS workflow to HEK293 cells led the detection and quantification of subunit distribution of 462 distinct protein complexes containing 2,127 proteins and identified novel complex variants such as assembly intermediates. The interactive platform, SECexplorer is presented to support custom complex‐centric exploration of SEC‐SWATH‐MS datasets. Graphical Abstract The study presents an integrated framework for targeted, complex‐centric analysis based on size exclusion chromatography (SEC) and SWATH/DIA mass spectrometry. The workflow facilitates the parallel detection of hundreds of prote