Adapter protein involved in asymmetrical cell division and cell polarization processes. May play a role in the formation of epithelial tight junctions. The PARD6-PARD3 complex links GTP-bound Rho small GTPases to atypical protein kinase C proteins (By similarity). Interacts with PARD3 (Probable). Interacts with GTP-bound forms of CDC42, RHOQ/TC10 and RAC1 (By similarity). Interacts with the N-terminal part of PRKCI and PRKCZ (By similarity). The pseudo-CRIB domain together with the PDZ domain is required for the interaction with Rho small GTPases. Belongs to the PAR6 family.