This detailed new edition presents the latest developments of the main pillars of protein analysis, namely sample preparation, separation, and characterization. Core areas in this volume are protocols for the analysis of post-translational modifications and protein interaction partners, followed by sophisticated procedures to enrich for extracellular vesicles and organelles, along with several types of protein immuno-assays complemented by various methods for the characterization of antibodies and host-cell protein analysis. Last but not least, a few standard sample preparation protocols and recent advances concerning immuno-chemical detection of proteins are included as well. Written for the highly successful Methods in Molecular Biology series, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls.