However, immunoelectron microscopy indicates that paracingulin is not only localized in the TJ but also in the adherens junctions (AJ) depending on tissue type.

The proteins present in this complex play a role in many cellular processes i.e., in the adhesion and barrier function of epithelia, the organization and dynamics of the cytoskeleton, as well as the regulation of Rho-GTPase family.

[16] Association of paracingulin with the apical junctional complex is a highly dynamic process, and requires the integrity of both microtubule and actin cytoskeleton.

Unlike cingulin, paracingulin associates with actin filaments[8][9] in different types of culture cells and its localization at the apical junctional complex is perturbed by treatment with the microtubule drug nocodazole.

Depletion of paracingulin by shRNA in cultured kidney cells (MDCK) does not alter tight or adherens junctions organization.

Indeed, paracingulin can interact with and thus recruit Tiam1 to the junction, allowing the local activation of Rac1[10] Both paracingulin depletion and overexpression experiments also led to the conclusion that it also interacts with and recruits SH3BP1, which is an inactivator of the Rho GTPases Cdc42 and Rac1 involved in epithelial junction formation in association with the filamentous actin-capping protein CapZ, by controlling actin-driven membrane remodeling.

[16] Paracingulin thus really acts as an adaptator for Rho GTPase regulators at the apical junctional region, and possibly at other cellular sites, because of its extra-junctional localization.

In addition, cingulin and paracingulin have similar dynamics, partially overlapping subcellular localizations, and distinct interactions with the actin and microtubule cytoskeletons.

[9] The CGNL1 gene is conserved in chimpanzee, rhesus monkey, dog, cow, mouse, rat, chicken, and zebrafish.