Adapter protein involved in asymmetrical cell division and cell polarization processes. Probably involved in formation of epithelial tight junctions. Association with PARD3 may prevent the interaction of PARD3 with F11R/JAM1, thereby preventing tight junction assembly. The PARD6-PARD3 complex links GTP-bound Rho small GTPases to atypical protein kinase C proteins. Interacts with PARD3. Interacts with GTP-bound forms of CDC42 and RAC1. Interacts with GTP-bound RHOQ/TC10. Interacts with PALS1 (By similarity). Interacts with the N-terminal part of PRKCI and PRKCZ. Part of a complex with PARD3, CDC42 or RAC1 and PRKCI or PRKCZ. Part of a complex with LLGL1 and PRKCI. Interacts with PARD3B. Interacts with ECT2. Expressed in pancreas and in both adult and fetal kidney. Weakly expressed in placenta and lung. Not expressed in other tissues. The pseudo-CRIB domain together with the PDZ domain is required for the interaction with Rho small GTPases. The PDZ domain mediates interaction with PALS1. Belongs to the PAR6 family.