Essentielli aminohappo metioniini (Met, M) palautuu reduktaaseilla sulfoxidimuodoistaan.

 MSRA  (8p23.1), 235 a.a.. "Mithochondrial peptide methionine sulfoxide reductase".

https://www.genecards.org/cgi-bin/carddisp.pl?gene=MSRA&keywords=Methionine-S-sulfoxide,reductase;

• Mitochondrial Peptide Methionine Sulfoxide Reductase ^{3 4}
• Peptide-Methionine (S)-S-Oxide Reductase ^{3 4}
• Peptide Met(O) Reductase ^{3 4}

 This gene encodes a ubiquitous and highly conserved protein that carries out the enzymatic reduction of methionine sulfoxide to methionine. Human and animal studies have shown the highest levels of expression in kidney and nervous tissue. The protein functions in the repair of oxidatively damaged proteins to restore biological activity. Alternative splicing results in multiple transcript variants. [provided by RefSeq, May 2014]

MSRB1 (16p13.3), 116 a.a. "Methionine-R-sulfoxide reductase B1"

Cofactor Zn++.

 https://www.genecards.org/cgi-bin/carddisp.pl?gene=MSRB1&keywords=Methionine-S-sulfoxide,reductase;

• GeneCards Symbol: MSRB1 ²
• Methionine Sulfoxide Reductase B1 ^{2 3 5}
• SELENOX ^{2 3 5}
• SELENOR ^{2 3 5}
• SEPX1 ^{3 4 5}
• SepR ^{2 3 5}
• SelX ^{2 4 5}
• Methionine-R-Sulfoxide Reductase B1 ^{3 4}
• Selenoprotein X, 1 ^{2 3}

The protein   encoded by this gene belongs to the methionine-R-sulfoxide reductase B (MsrB) family. Members of this family function as repair enzymes that protect proteins from oxidative stress by catalyzing the reduction of methionine-R-sulfoxides to methionines. This protein is highly expressed in liver and kidney, and is localized to the nucleus and cytosol. It is the only member of the MsrB family that is a selenoprotein, containing a selenocysteine (Sec) residue at its active site. It also has the highest methionine-R-sulfoxide reductase activity compared to other members containing cysteine in place of Sec. Sec is encoded by the UGA codon, which normally signals translation termination. The 3' UTRs of selenoprotein mRNAs contain a conserved stem-loop structure, designated the Sec insertion sequence (SECIS) element, that is necessary for the recognition of UGA as a Sec codon, rather than as a stop signal. A pseudogene of this locus has been identified on chromosome 19. [provided by RefSeq, Aug 2017]

Methionine-sulfoxide reductase that specifically reduces methionine (R)-sulfoxide back to methionine. While in many cases, methionine oxidation is the result of random oxidation following oxidative stress, methionine oxidation is also a post-translational modification that takes place on specific residue. Acts as a regulator of actin assembly by reducing methionine (R)-sulfoxide mediated by MICALs (MICAL1, MICAL2 or MICAL3) on actin, thereby promoting filament repolymerization. Plays a role in innate immunity by reducing oxidized actin, leading to actin repolymerization in macrophages.

MSRB2, (10p12.2), 182 a.a., " Methionine-(R)- sulfoxide reductase B2, mithochondrial".

Cofaxtor Zn.

https://www.genecards.org/cgi-bin/carddisp.pl?gene=MSRB2&keywords=Methionine-S-sulfoxide,reductase; 

Methionine-sulfoxide reductase that specifically reduces methionine (R)-sulfoxide back to methionine. While in many cases, methionine oxidation is the result of random oxidation following oxidative stress, methionine oxidation is also a post-translational modification that takes place on specific residue. Upon oxidative stress, may play a role in the preservation of mitochondrial integrity by decreasing the intracellular reactive oxygen species build-up through its scavenging role, hence contributing to cell survival and protein maintenance. ( MSRB2_HUMAN,Q9Y3D2 )

MSRB3,  (12q14.3) ,192 a.a.,  "Methionine R-Sulfoxide reductase B3"

https://www.genecards.org/cgi-bin/carddisp.pl?gene=MSRB3

https://www.genecards.org/cgi-bin/carddisp.pl?gene=MSRB2&keywords=Methionine-S-sulfoxide,reductase;  (Tästä on löydetty aktiivisuutta Stafylokokki aureusta vastaan)