This is an immunoglobulin like domain found at the C-terminal region of EcpB. It is a periplasmic chaperone which along with EcpE help assemble the E. coli common pilus (ECP) EcpA and EcpD subunits. The C-terminal domain is predicted to contain residues that might be involved in binding a C-terminal carboxylate anchor [1].

1: Structural Insight into Archaic and Alternative Chaperone-Usher Pathways Reveals a Novel Mechanism of Pilus Biogenesis. Pakharukova N, Garnett JA, Tuittila M, Paavilainen S, Diallo M, Xu Y, Matthews SJ, Zavialov AV; PLoS Pathog. 2015;11:e1005269. PMID:26587649