A Monoclonal Antibody that Specifically Recognizes RAX/PACT Protein

Targeting a Protein that Initiates the Physiological Stress Response

Scientists at the University of Florida have developed a wide variety of monoclonal and polyclonal antibodies, cell lines, vectors and biological materials that can be used in other research projects. Anyone interested in accessing these materials via a license from the University of Florida should contact our office to make arrangements. Murine RAX (PKR Activator X) protein and its human ortholog PACT (Protein Activator of Interferon-induced Protein Kinase) are the only known cellular activators of the interferon-induced dsRNA-dependent protein kinase, PKR. RAX and PACT are 98% identical in amino acid sequence. In addition, RAX/PACT associates with Dicer to form the RNA-induced silencing complex (RISC) and promote small RNA-mediated gene silencing. RAX is phosphorylated on serine 18 during cellular stress applications and this phosphorylation is required for PKR activation and consequent translation inhibition during events such as growth factor deprivation, cytotoxic cytokine or chemotherapy treatment and viral infection. In addition, exogenous expression of RAX(S18A) promotes anchorage-independent growth of fibroblast cell lines, indicating that RAX phosphorylation is required for normal cellular growth regulation. Two peptides (corresponding to RAX amino acids 13 to 25, but one peptide contained phosphoserine instead of serine at position 18) were used as antigens to generate a hybridoma cell line producing a monoclonal antibody that recognizes both non-phosphorylated and phosphorylated RAX.