PARP4 (Poly(ADP-ribose) polymerase 4), also known as ADPRTL1 or vPARP, is a member of the PARP enzyme family involved in DNA repair, genomic stability, and stress response. Unlike PARP1/2. PARP4 is less characterized but is implicated in diverse cellular processes, including double-strand break repair, transcriptional regulation, and immune response. Structurally, it contains a conserved catalytic PARP domain, a BRCA1-interacting domain, and a vault protein-interacting domain, linking it to vault ribonucleoprotein particles. PARP4's dual role in cancer is debated: it may act as a tumor suppressor by promoting DNA repair or as an oncogene via pro-survival signaling in certain contexts. Dysregulation is associated with hematologic malignancies, breast cancer, and ovarian cancer.
PARP4 antibodies are essential tools for studying its expression, localization, and interactions. They enable applications like Western blotting, immunofluorescence, and immunohistochemistry to assess PARP4 levels in cancer tissues, often revealing overexpression in drug-resistant tumors. Research also explores PARP4's potential as a biomarker for PARP inhibitor therapies (e.g., olaparib), though its resistance mechanisms differ from PARP1/2. Recent studies highlight its role in antiviral immunity and inflammation, expanding interest in PARP4-targeted therapeutic strategies. However, functional redundancy within the PARP family and context-dependent roles necessitate careful interpretation of antibody-based findings.