Expression analysis and mitochondrial targeting properties of the chicken manganese-containing superoxide dismutase

Byung Whi Kong, Hyunggee Kim, Douglas N. Foster

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16 Citations (Scopus)


Manganese-containing superoxide dismutase (MnSOD) is a major detoxifying enzyme that functions in cellular oxygen metabolism by converting O2- to H2O2. A cDNA encoding the chicken MnSOD (cMnSOD) has been isolated from a chicken embryo fibroblast (CEF) cell cDNA library. The cloned cMnSOD is 1102 bp in length with an open reading frame (ORF) of 224 amino acids that includes a 26-amino-acid 5′-proximal mitochondrial targeting sequence (MTS). The mature 198-amino-acid region of the cMnSOD is highly conserved among various mammalian species. Two cMnSOD mRNA species (1.2 and 1.0 kb) were expressed in most of the tissues and organs analyzed, with the highest expression levels found in brain, kidney, and heart tissues. Compared to earlier stages of development, expression of cMnSOD was highest in day 13 embryonic heart tissue, and was maintained until post-hatch. Exogenously introduced cMnSOD-GFP fusion constructs (which included the MTS) clearly accumulated in the mitochondria of chicken cells, as expected. Surprisingly, the cMnSOD MTS signal, which displays little similarity to mammalian MTS sequences, enabled cMnSOD-GFP fusion proteins to target mitochondria not only from different cell types (fibroblastic and epithelial), but from a number of mammalian species (human, mouse, and pig). This suggests that specific amino acid motifs within the MTS domain may be more important than the overall sequence similarities for mitochondrial targeting.

Original languageEnglish
Pages (from-to)98-108
Number of pages11
JournalBiochimica et Biophysica Acta - Gene Structure and Expression
Issue number1
Publication statusPublished - 2003 Jan 3
Externally publishedYes

Bibliographical note

Funding Information:
We thank Jim Farris, Linda Foster, and Shelly Christman (University of Minnesota) for their helpful discussions. This work was supported, in part, by USDA/NRICGP grant no. 9603280 and a grant from Syntro/Schering Plough to D.N.F.


  • Antioxidant
  • Chicken
  • Mitochondrial targeting sequence
  • MnSOD

ASJC Scopus subject areas

  • Structural Biology
  • Biophysics
  • Biochemistry
  • Genetics


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