| Budget Amount *help |
¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 2001: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2000: ¥3,000,000 (Direct Cost: ¥3,000,000)
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| Research Abstract |
When this grant application was submitted, preliminary data showed modification of α-isoform of inhibitory protein (I_KB_α) by cell treatment with taurine chloramine (TauCl) that was judged by band shift observed in Western blots, suppression of I_KB_α degradation in response to stimulation and subsequent inhibition of nuclear factor _KB (NF_KB) activation. This suppression of I_KB_α degradation seemed to be due to its chlorination by TauCl. Therefore, this research was started with seeking amino acid residues of I_KB_α that are chlorinated by TauCl. Because the amino acid residue that is most easily chlorinated is tyrosine, tyrosine residues (eight tyrosine residues in I_KB_α) were mutated to alanine one by one. However, a mutant whose tyrosine residues were all converted to alanine showed band shift by TauCl treatment, indicated that tyrosine residue is not the chlorination site. Similar experiments were performed in regard to tryptophan. However, tryptophan was not a chlorination site, either. Then, amino acid residues modified by TauCl were further searched with deletion mutants of I_KB_α. As a result, the 45th methionine was found to be a site susceptible to TauCl modification. This methionine modification was estimated to be oxidation to form methionine sulfoxide by analysis of an oligo-peptide containing the 45th methionine with high performance liquid chromatography and mass spectrometry. These results lead to a unique hypothesis that protein oxidation at methionine residues may play a part in the cellular signal transduction.
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