Par-3 family cell polarity regulator beta (PARD3B)

Par-3 family cell polarity regulator beta (PARD3B), also known as PAR3B or Par-3-like, is a conserved adapter protein encoded by the PARD3B gene. It is a member of the Par-3/Baz family of polarity proteins and localizes predominantly at adherens junctions in epithelial tissues, particularly in the basal layer of stratified epithelia where many stem cells reside[1][3]. PARD3B is structurally similar to its paralog PARD3 but is functionally distinct, as it does not bind PAR6 or aPKC—unlike classic apically localized Par-3. Instead, PARD3B is implicated in the spatial organization of cell adhesion molecules (notably E-cadherin), the regulation of signaling cascades at cell junctions (e.g., via Src family kinases), and maintenance of epithelial stem cell populations[2][3][1]. Loss or dysregulation of PARD3B has been associated with impaired epithelial proliferation, increased cell death, and altered responses to chemotherapy. Overexpression of PARD3B is correlated with advanced tumor stage and poor prognosis in certain cancers[3]. It is considered a potential therapeutic target, particularly in oncology, and may serve as a biomarker for disease progression and treatment stratification[3].

Other names

PAR3BALS2CR19PAR3LPAR3betaAmyotrophic lateral sclerosis 2 chromosomal region candidate gene 19Partitioning defective 3-like proteinPAR3-L proteinPartitioning-defective 3-betaPar3L

Not applicable—no accredited direct pharmacological agents currently target PARD3B; functional modulation impacts junctional signaling and oncogenic signaling pathways