Protein interaction network between type VI secretion subunits. The localization and topologies of the core components of the T6SS are represented. Arrows indicate interactions detected among the subunits by biochemical/structural (blue) or two-hybrid approaches (red). The letter accompanying the arrow denotes the system where the interaction was detected. The membrane-associated subassembly and the bacteriophage-like subassembly are outlined in green and pink, respectively. The question mark represents subunits for which the localization has not been investigated. Relevant studies are discussed in the text. Abbreviations: T6SS, type VI secretion system; A, Agrobacterium tumefaciens; B, Burkholderia cenocepacia; E, Edwardsiella tarda; EA, enteroaggregative Escherichia coli; P, Pseudomonas aeruginosa; S, Salmonella enterica; Sm, Serratia marcescens; V, Vibrio cholerae; Y, Yersinia pseudotuberculosis Please add references (7, 12, 16a, 31a, 35, 42, 56, 64, 70, 70a, 76, 81, 84, 86 and 116)