Probably plays a role in the formation and regulation of the tight junction (TJ) paracellular permeability barrier, possibly by linking ZO proteins to the actomyosin cytoskeleton. Parallel homodimer (By similarity). Interacts with TJP1/ZO1 and TJP2/ZO2 (By similarity). Localizes to the apical junction complex composed of tight and adherens junctions. Deletion of the TJP1/ZO1 interaction motif (ZIM) decreases but does not abolish colocalization with TJP1/ZO1. Belongs to the cingulin family. It is uncertain whether Met-1 or Met-9 is the initiator. Truncated N-terminus.