A thiol-specific antioxidant and sequence homology to various proteins of unknown function.
Yeast and mammalian cells contain a 25 kDa enzyme that protects cellular components against oxidative damage from a system capable of generating reactive sulfur species, but not from a system that generates only reactive oxygen species. Yeast and rat cDNAs corresponding to this thiol-specific antioxidant (TSA) have been cloned and sequenced. Rat TSA is 65.3% identical and 76.2% similar to yeast TSA in amino acid sequence. A search of the GenBank database revealed 12 additional TSA-like proteins, which show sequence identity to rat TSA ranging from 31 to 76%. Except for the AhpC protein identified in Salmonella typhimurium, none of the TSA-like proteins is associated with known cellular functions. AhpC, which exhibits approximately 40% sequence identity to TSA, has been proposed to be a catalytic component of alkyl hydroperoxide reductase. Alignment of rat and yeast TSA with the TSA-like sequences revealed two conserved cysteine residues, one conserved in all 14 sequences and the other in 12 sequences. The most conserved cysteine is located in a well-conserved motif of (hydrophobic residue)6-Pro-non-conserved-residue-Asp-Phe-Thr-Phe-Val-Cys-Pro-Thr-Glu- hydrophobic residue. These results suggest that the TSA-like proteins of previously unknown function may represent a widely distributed family of antioxidants with functions similar to those of TSA and AhpC.
Chae
H Z
HZ
Laboratory Biochemistry, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
Rhee
S G
SG
D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry; D003001:Cloning, Molecular; D017124:Conserved Sequence; D008969:Molecular Sequence Data; D010544:Peroxidases; D054464:Peroxiredoxins; D011506:Proteins / Q000737:chemistry* / Q000235:genetics; D051381:Rats; D012441:Saccharomyces cerevisiae; D017421:Sequence Analysis; D017385:Sequence Homology; D013438:Sulfhydryl Compounds
D011506:Proteins; D013438:Sulfhydryl Compounds; D010544:Peroxidases; D054464:Peroxiredoxins