PI31/PSMF1 Antibody #91788

Proteasome-binding protein PI31 (Proteasomal Inhibitor of 31kD) is encoded by the PSMF1 gene and regulates proteasome function in the cell, which is essential for cell function and survival. Regulated degradation of intracellular proteins is mediated by the ubiquitin-proteasome system (UPS) by a multi-step process (1,2). First, protein to be degraded is tagged with a chain of ubiquitin molecules. Ubiquitinated proteins are then cleaved into small peptides by the 26S proteasome. Proteasome activity by the UPS is regulated at additional levels, including transcriptional expression of proteasomal proteins, posttranslational modification, and by various regulatory proteins. PI31/PSMF1 is a structurally conserved proteasome regulator that binds to the 20S proteasome and functions to inhibit 20S proteasome hydrolysis of small peptides (3,4). Unexpectedly, PI31/PSMF1 promotes UPS-mediated protein breakdown in vivo, suggesting additional proteasome regulatory functions beyond inhibition of the 20S proteasome (5). PI31/PSMF1 also serves as an adaptor protein to transport proteasomes via cellular protein motors (6,7). This process may be particularly important in neurons where local proteasomal degradation at distal tips of neurons may play a critical role in the maintenance of neuronal architecture, circuitry, and function.