A Novel Mutation of Human Liver Alanine:Glyoxylate Aminotransferase Causes Primary Hyperoxaluria Type 1: Immunohistochemical Quantification and Subcellular Distribution
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- Kawai Chikage
- Department of Biochemistry, Kawasaki Medical School
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- Minatogawa Yohsuke
- Department of Biochemistry, Kawasaki Medical School
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- Akiyoshi Hidetaka
- Department of Pediatrics, Medical School of Fukuoka University
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- Hirose Shinichi
- Department of Pediatrics, Medical School of Fukuoka University
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- Suehiro Tsunatoshi
- Department of General Surgical Science, Gunma University Graduate School of Medicine
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- Tone Shigenobu
- Department of Biochemistry, Kawasaki Medical School
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抄録
A novel alanine:glyoxylate aminotransferase (AGT) mutation involved in primary hyperoxaluria type 1 (PH1) was studied in Japanese patients. Two mutations in exon 7, c.751T>A and c.752G>A, lead to a W251K amino acid substitution. Proband 1 (patient 1) was homozygous for the W251K mutation allele (DDBJ Accession No. AB292648), and AGT-specific activity in the patient’s liver was very low. To reveal the cause of the low enzymatic activity, the intracellular localization of AGT (W251K) was studied using immunohistochemistry and immunoelectron microscopy. The latter analysis showed that patient 2 had only one-fifth of the normal AGT expression per catalase, suggesting impairment of AGT (W251K) dependent transport into peroxisomes. Peroxisomal transport of human AGT is believed to be dependent on the presence of the type 1 peroxisomal targeting sequence. The C-terminal tripeptide of AGT, KKL is necessary for peroxisomal targeting. In cultured cells, EGFP-AGT (W251K) localized both in the peroxisome and cytosol. These results were consistent with the data obtained from liver analysis of patient 2. The subcellular distribution of AGT (W251K) and the results from a random mutagenesis study suggest that KKL is necessary for peroxisomal targeting of human AGT, but additional signal other than KKL may be necessary.<br>
収録刊行物
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- Ａｃｔａ Ｈｉｓｔｏｃｈｅｍｉｃａ ｅｔ Ｃｙｔｏｃｈｅｍｉｃａ
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Ａｃｔａ Ｈｉｓｔｏｃｈｅｍｉｃａ ｅｔ Ｃｙｔｏｃｈｅｍｉｃａ 45 (2), 121-129, 2012
日本組織細胞化学会