MSRB1
Description
The MSRB1 (methionine sulfoxide reductase B1) is a protein-coding gene located on chromosome 16.
MsrB1, also known as Selenoprotein X, is an enzyme encoded by the SEPX1 gene in humans. It is a selenoprotein, containing a selenocysteine (Sec) residue at its active site. The Sec is encoded by the UGA codon, normally signaling translation termination. The 3' UTR of selenoprotein genes has a common stem-loop structure called the SECIS element, crucial for recognizing UGA as a Sec codon rather than a stop signal. MsrB1 belongs to the methionine sulfoxide reductase B (MsrB) family and is expressed in various adult and fetal tissues.
MsrB1 is a methionine sulfoxide reductase that specifically reduces methionine (R)-sulfoxide back to methionine. This activity is crucial for various cellular processes. Methionine oxidation can occur due to random oxidative stress, but it can also be a targeted post-translational modification on specific residues. MsrB1 acts as a regulator of actin assembly by reducing methionine (R)-sulfoxide, which is often mediated by MICAL proteins (MICAL1, MICAL2, or MICAL3) on actin. This reduction promotes filament repolymerization. Additionally, MsrB1 plays a role in innate immunity by reducing oxidized actin, leading to actin repolymerization in macrophages.
MSRB1 is also known as HSPC270, SELENOR, SELENOX, SELR, SELX, SEPX1, SepR.
