This collection of practical, cutting-edge techniques for the study of cell signaling provides detailed, step-by-step instructions, helpful notes, and troubleshooting tips that make even the most powerful of the newest techniques readily reproducible. The protocols presented include the use of peptide libraries to study transmembrane signaling; the use of single-cell assays to analyze signal transduction pathways; the reconstitution of signaling complexes; methods for analyzing protein–protein interactions, and more. Introductory reviews explain the basic theory and enable researchers new to the area to rapidly gain understanding, as well as command of the practical knowledge and expertise afforded by the protocols. Transmembrane Signaling Protocols makes available to all researchers the many state-of-the-art techniques that have recently led to landmark discoveries in transmembrane signaling.