tailieunhanh - Báo cáo khoa học: Molecular basis of perinatal hypophosphatasia with tissue-nonspecific alkaline phosphatase bearing a conservative replacement of valine by alanine at position 406 Structural importance of the crown domain

Hypophosphatasia, a congenital metabolic disease related to the tissue-non-specific alkaline phosphatase gene (TNSALP), is characterized by reduced serum alkaline phosphatase levels and defective mineralization of hard tis-sues. A replacement of valine with alanine at position 406, located in the crown domain of TNSALP, was reported in a perinatal form of hypophos-phatasia. | ỊFEBS Journal Molecular basis of perinatal hypophosphatasia with tissue-nonspecific alkaline phosphatase bearing a conservative replacement of valine by alanine at position 406 Structural importance of the crown domain Natsuko Numa1 Yoko Ishida2 Makiko Nasu3 Miwa Sohda2 Yoshio Misumi4 Tadashi Noda1 and Kimimitsu Oda2 5 1 Division of Pediatric Dentistry Niigata University Graduate Schoolof Medicaland DentalSciences Japan 2 Division of OralBiochemistry Niigata University Graduate Schoolof Medicaland DentalSciences Japan 3 Division of OralHealth in Aging and Fixed Prosthodontics Niigata University Graduate Schoolof Medicaland DentalSciences Japan 4 Department of Cell Biology Fukuoka University Schoolof Medicine Japan 5 Center for Transdisciplinary Research Niigata University Japan Keywords crown domain glycosylphosphatidylinositol hypophosphatasia raft tissue-nonspecific alkaline phosphatase Correspondence K. Oda Division of OralBiochemistry Niigata University Graduate Schoolof Medicaland DentalSciences 2-5274 Gakkocho-dori Niigata 951-8514 Japan Fax 81 25 227 0805 Tel 81 25 227 2827 E-mail oda@ Received 30 November 2007 revised 18 January 2008 accepted 19 March 2008 doi Hypophosphatasia a congenital metabolic disease related to the tissue-nonspecific alkaline phosphatase gene TNSALP is characterized by reduced serum alkaline phosphatase levels and defective mineralization of hard tissues. A replacement of valine with alanine at position 406 located in the crown domain of TNSALP was reported in a perinatal form of hypophos-phatasia. To understand the molecular defect of the TNSALP V406A molecule we examined this missense mutant protein in transiently transfected COS-1 cells and in stable CHO-K1 Tet-On cells. Compared with the wild-type enzyme the mutant protein showed a markedly reduced alkaline phosphatase activity. This was not the result of defective transport and resultant degradation of TNSALP V406A in the .