Abstract |
Based on studies of hypophosphatasia, which is a systemic skeletal disorder resulting from tissuenonspecific alkaline phosphatase (TNSALP) deficiency, TNSALP was suggested to be indispensable for bone mineralization. Recently, we demonstrated that there was a significant difference in bone mineral density (BMD) among haplotypes, which was lowest among TNSALP (787T [Tyr-246Tyr]) homozygotes, highest among TNSALP (787T > C [Tyr246His]) homozygotes, and intermediate among heterozygotes. To analyze protein translated from the TNSALP gene 787T > C, we performed the biosynthesis of TNSALPs using TNSALP cDNA expression vectors. TNSALP (787T) and TNSALP (787T > C) were synthesized similarly as a high- mannose-type 66-kDa form, becoming an 80-kDa form. Expression of the human 787T > C TNSALP gene using the cultured mouse marrow stromal cell line ST2 demonstrated that the protein translated from 787T > C exhibited an ALP-specific activity similarly to that of 787T. Interestingly, the Km value for TNSALP in ST2 cells transfected with the 787T > C TNSALP gene was decreased significantly compared to that of cells carrying the 787T gene (P < 0.01). These results suggest that the significant difference in Km values between the proteins translated from 787T > C and 787T may contribute to regulatory effects on bone metabolism.
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Authors | Natsuko Sogabe, Kimimitsu Oda, Hiroyuki Nakamura, Hideo Orimo, Hisashi Watanabe, Takayuki Hosoi, Masae Goseki-Sone |
Journal | Biomedical research (Tokyo, Japan)
(Biomed Res)
Vol. 29
Issue 4
Pg. 213-9
(Aug 2008)
ISSN: 1880-313X [Electronic] Japan |
PMID | 18724009
(Publication Type: Journal Article)
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Chemical References |
- Isoenzymes
- Alkaline Phosphatase
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Topics |
- Alkaline Phosphatase
(genetics, metabolism)
- Animals
- Bone Density
(genetics)
- Cell Line
- Haplotypes
- Humans
- Hypophosphatasia
(genetics, metabolism)
- Isoenzymes
(genetics, metabolism)
- Mice
- Models, Molecular
- Polymorphism, Genetic
- Protein Conformation
- Stromal Cells
(cytology, physiology)
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