This volume in the Subcellular Biochemistry (SCBI) series is a continuation of several previous volumes devoted to the structural and functional study of protein complexes. The expanding nature of this field of study, derived mainly from X-ray crystallography and electron cryomicroscopy, justifies the continuing expansion of coverage in an almost encyclopaedic manner within the SCBI series. Experienced and active researchers in the field shed light on the biology of protein complexes involved in important cellular functions from different perspectives, such as AcrAB-TolC, and CST. Other topics covered are: the Toxin-Antitoxin systems in cell survival, the role of the ATPases CueR and RUVBL1-RUVBL2 in the regulation of gene expression, complexes with multiple functions in the cell such as VCP/p97 or the Vault complex, FtsA and FtsZ in bacterial cell division, GATOR1 and GATOR2 in amino acid sensing, TRPA1 and the Serotonin Transporter in signaling, oligomeric structures in eukaryotic cells such as amyloids and invertases, among others. The book is richly illustrated, the result of an impressive integration of structural data from X-ray crystallography and cryo-electron microscopy. Functional aspects of protein-protein interactions are also featured prominently, providing a valuable contribution for researchers and scholars. Chapter 13 is available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.