Human mitochondrial thioredoxin reductase cDNA cloning, expression and genomic organization.
We have isolated a 1918-bp cDNA from a human adrenal cDNA library which encodes a novel thioredoxin reductase (TrxR2) of 521 amino acid residues with a calculated molecular mass of 56.2 kDa. It is highly homologous to the previously described cytosolic enzyme (TrxR1), including the conserved active site CVNVGC and the FAD-binding and NADPH-binding domains. However, human TrxR2 differs from human TrxR1 by the presence of a 33-amino acid extension at the N-terminus which has properties characteristic of a mitochondrial translocation signal. Northern-blot analysis identified one mRNA species of 2.2 kb with highest expression in prostate, testis and liver. We expressed human TrxR2 as a fusion protein with green fluorescent protein and showed that in vivo it is localized in mitochondria. Removal of the mitochondrial targeting sequence abolishes the mitochondrial translocation. Finally, we determined the genomic organization of the human TrxR2 gene, which consists of 18 exons spanning about 67 kb, and its chromosomal localization at position 22q11.2.
Miranda-Vizuete
A
A
Department of Biosciences at Novum, Karolinska Institute, Huddinge, Sweden.
Damdimopoulos
A E
AE
Pedrajas
J R
JR
Gustafsson
J A
JA
Spyrou
G
G
D020413:3' Untranslated Regions / Q000235:genetics; D000311:Adrenal Glands / Q000201:enzymology*; D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics; D003001:Cloning, Molecular; D017124:Conserved Sequence; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics*; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000235:genetics; D016415:Sequence Alignment; D013880:Thioredoxin-Disulfide Reductase / Q000737:chemistry / Q000235:genetics*
D020413:3' Untranslated Regions; D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D013880:Thioredoxin-Disulfide Reductase