This domain is found at the N-terminal of TadZ from Eubacterium rectale and similar bacterial proteins. TadZ is is an essential component of the Tad secretion system that probably functions as a localization factor. This protein is composed of two domains, both of which have lost its active sites. This entry represents the N-terminal atypical receiver domain (ARD), which is structurally similar to the RD of response regulators such as the chemotaxis protein CheY [1].

1: Structure of the pilus assembly protein TadZ from Eubacterium rectale: implications for polar localization. Xu Q, Christen B, Chiu HJ, Jaroszewski L, Klock HE, Knuth MW, Miller MD, Elsliger MA, Deacon AM, Godzik A, Lesley SA, Figurski DH, Shapiro L, Wilson IA; Mol Microbiol. 2012;83:712-727. PMID:22211578