Partitioning Defective 3 Homolog (PARD3)

PARD3 and PARD6, in turn, formed a quaternary complex with protein kinase C-zeta (PRKCZ) and CDC42. Fluorescence microscopy demonstrated that PARD3 colocalizes with the tight junction protein ZO1 (TJP1), and this colocalization could be disrupted by the expression of the PARD3-binding region of PARD6. PARD proteins, which were first identified in C. elegans, are essential for asymmetric cell division and polarized growth, whereas CDC42 (MIM 116952) mediates the establishment of cell polarity. The CDC42 GTPase, which is controlled by nucleotide exchange factors (GEFs; see MIM 606057) and GTPase-activating proteins (GAPs; see MIM 604980), interacts with a large set of effector proteins that typically contain a CDC42/RAC (MIM 602048)-interactive binding (CRIB) domain.