BACKGROUND Prostate apoptosis response, PAR-4, encodes a 38 kDa protein that belongs to the family of immediate-early gene products, which include c-Myc, c-Fos, c-Jun, Nur77, and EGR-1. Unlike the other immediate-early gene products, par-4 expression appears to be induced exclusively by apoptotic stimuli.1 The carboxyl-terminal portion of the Par-4 protein contains a death domain homologous to that of Fas and TRADD and may, therefore, initiate a cascade of events analogous to that of other death domain-containing proteins. PAR-4 has been shown to interact with several proteins known to modulate apoptosis, including protein kinase Czeta, Bcl-2, and caspase-8. A rapid increase in Par-4 levels occurs in neurons undergoing apoptosis in a variety of paradigms, including trophic factor withdrawal, and exposure to oxidative and metabolic insults. Par-4, which can be induced at the translational level, acts at an early stage of the apoptotic cascade prior to caspase activation and mitochondrial dysfunction. The mechanism whereby Par-4 promotes apoptosis may involve inhibition of the antiapoptotic transcription factor NF-kappaB and suppression of Bcl-2 expression and/or function.2 Within the death domain of Par-4 is a leucine zipper domain that appears to mediate protein–protein interactions. Because of the widespread up-regulated expression of par-4 in neuronal cells induced to undergo apoptosis, it was suggested that the Par-4 protein may play a role in the pathogenesis of neurodegenerative disorders.3
1. Rangnekar VM: Apoptosis 3:61-66, 1998.
2. El-Guendy N & Rangnekar VM: Exp. Cell Res. 283:51-66, 2003.
3. Guo Q et al.: J. Biol. Chem. 276: 16040-16044, 2001.
Products are for research use only. They are not intended for human, animal, or diagnostic applications.
Recombinant fragment of human PAR-4 (aa1-330) expressed in E. Coli.
Species & predicted
reactivity ( ):
Weight of protein:
Detects endogenous levels of PAR-4 proteins in various cell lysates.
Store at 4° C for frequent use; at -20° C for at least one year.
*Optimal working dilutions must be determined by end user.