Background
Cellular asymmetry is critical for the development of multicellular organisms. PARD (partitioning-defective) proteins play important roles in asymmetric cell division and polarized growth. PARD3A (partitioning-defective 3), also known as Baz, ASIP (atypical PKC isotype-specific-interacting protein), PAR3, PARD3, PAR3α, Bazooka, SE2-5T2, SE2-5L16 or SE2-5LT1, is a 1,356 amino acid protein that contains three PDZ domains and belongs to the PAR3 family of proteins. Expressed in a wide variety of tissues, PARD3A colocalizes with PARD6A/B and PKC ι at epithelial tight junctions and is believed to function as an adapter protein with an important role in the formation of normal tight junctions at epithelial cell-cell contacts. Due to alternative splicing events, PARD3A exists in at least ten isoforms, namely isoform A, isoform B, isoform C, isoform D, isoform E, isoform F, isoform Lb, isoform Sa, isoform Sb and isoform 10.