This domain is found in the C-terminal region of the Tc toxin TcA, present in Photorhabdus luminescens. Tc Toxin complexes bind to the cell surface, are endocytosed and perforate the host endosomal membrane by forming channels that translocate toxic enzymes into the host. This domain is responsible for binding to toxin TcB. Binding of TcA to TcB/TcC opens the beta-propeller gate [1].

1: Mechanism of Tc toxin action revealed in molecular detail. Meusch D, Gatsogiannis C, Efremov RG, Lang AE, Hofnagel O, Vetter IR, Aktories K, Raunser S; Nature. 2014;508:61-65. PMID:24572368