Methionine-R-sulfoxide reductase B3 (MSRB3)

Methionine-R-sulfoxide reductase B3 (MSRB3) is an enzyme responsible for the stereospecific reduction of methionine-R-sulfoxide, repairing proteins that have undergone oxidative damage and contributing to cellular defense against reactive oxygen species[1][2][4][5]. In humans, MSRB3 exists as two isoforms: one targeted to the endoplasmic reticulum (ER) and another to mitochondria, with tissue-specific functions such as maintaining hearing and synaptic vesicle health[2][5]. Its dysfunction, via genetic mutation, is implicated in autosomal recessive, non-syndromic deafness (DFNB74), and altered expression is linked with Alzheimer’s disease progression. Structurally, the enzyme possesses a zinc-binding fold and an active site that requires electron transfer from resolved cysteine residues distant from the catalytic center[1]. No known small-molecule drugs specifically target MSRB3, but the enzyme’s essential roles in protein repair and redox signaling make it a subject of biomedical interest.

Other names

Methionine sulfoxide reductase B3MSRB3Methionine-R-sulfoxide reductase B3, mitochondrialUNQ1965/PRO4487MsrB3FLJ36866DKFZp686C1178DFNB74MsrB-3

Catalyzes the reduction of methionine-R-sulfoxide back to methionine, utilizing electron donors such as thioredoxin[1][5].