PSMB8 : proteasome 20S subunit beta 8
Description
The PSMB8 (proteasome 20S subunit beta 8) is a protein-coding gene located on chromosome 6.
The PSMB8 gene provides instructions for making one part (subunit) of cell structures called immunoproteasomes. Immunoproteasomes are specialized versions of proteasomes, which are large complexes that recognize and break down (degrade) unneeded, excess, or abnormal proteins within cells. This activity is necessary for many essential cell functions. While proteasomes are found in many types of cells, immunoproteasomes are located primarily in immune system cells. These structures play an important role in regulating the immune system's response to foreign invaders, such as viruses and bacteria. One of the primary functions of immunoproteasomes is to help the immune system distinguish the body's own proteins from proteins made by foreign invaders, so the immune system can respond appropriately to infection.Immunoproteasomes may also have other functions in immune system cells and possibly in other types of cells. They appear to be involved in some of the same fundamental cell activities as regular proteasomes, such as regulating the amount of various proteins in cells (protein homeostasis), cell growth and division, the process by which cells mature to carry out specific functions (differentiation), chemical signaling within cells, and the activity of genes. Studies suggest that, through unknown mechanisms, the subunit produced from the PSMB8 gene in particular may be involved in the maturation of fat cells (adipocytes).
The proteasome is a multi-enzyme complex that breaks down proteins. It is particularly active in breaking down proteins with specific amino acids (Arg, Phe, Tyr, Leu, and Glu) at a neutral or slightly basic pH. The proteasome uses energy (ATP) to perform this task. This subunit, PSMB8, is involved in breaking down proteins to create small pieces that are recognized by the immune system (antigen processing). PSMB8 is part of a specialized proteasome called the immunoproteasome. When PSMB8 replaces a related subunit (PSMB5) in the immunoproteasome, it increases the ability of the immunoproteasome to break down proteins after hydrophobic and basic residues. This subunit is also important for generating peptides that are made by joining two smaller pieces that were not originally next to each other in the original protein. PSMB8 is a key component in making cells sensitive to interferon gamma, a signaling molecule that activates the immune system. It is also important for programmed cell death (apoptosis) by breaking down a protein called MCL1, which prevents apoptosis. PSMB8 may also play a role in inflammation. In cancer cells, if the PSMB8 protein is altered, it can lead to a deficiency in the immunoproteasome. This subunit is also crucial for fat cell development.
PSMB8 is also known as ALDD, D6S216, D6S216E, JMP, LMP7, NKJO, PRAAS1, PSMB5i, RING10.
