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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2011-1-24
pubmed:abstractText
Mutations in the tissue-nonspecific alkaline phosphatase (TNSALP) gene are responsible for hypophosphatasia, an inborn error of bone and teeth metabolism associated with reduced levels of serum alkaline phosphatase activity. A missense mutation (c.346G>A) of TNSALP gene, which converts Ala to Thr at position 116 (according to standardized nomenclature), was reported in dominantly transmitted hypophosphatasia patients (A.S. Lia-Baldini et al. Hum Genet. 109 (2001) 99-108). To investigate molecular phenotype of TNSALP (A116T), we expressed it in the COS-1 cells or Tet-On CHO K1 cells. TNSALP (A116T) displayed not only negligible alkaline phosphatase activity, but also a weak dominant negative effect when co-expressed with the wild-type enzyme. In contrast to TNSALP (W, wild-type), which was present mostly as a non-covalently assembled homodimeric form, TNSALP (A116T) was found to exist as a monomer and heterogeneously associated aggregates covalently linked via disulfide bonds. Interestingly, both the monomer and aggregate forms of TNSALP (A116T) gained access to the cell surface and were anchored to the cell membrane via glycosylphosphatidylinositol (GPI). Co-expression of secretory forms of TNSALP (W) and TNSALP (A116T), which are engineered to replace the C-terminal GPI anchor with a tag sequence (his-tag or flag-tag), resulted in the release of heteromeric complexes consisting of TNSALP (W)-his and TNSALP (A116T)-flag. Taken together, these findings strongly suggest that TNSALP (A116T) fails to fold properly and forms disulfide-bonded aggregates, though it is indeed capable of interacting with the wild-type and reaching the cell surface, therefore explaining its dominant transmission.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0006-3002
pubmed:author
pubmed:copyrightInfo
Copyright © 2010 Elsevier B.V. All rights reserved.
pubmed:issnType
Print
pubmed:volume
1812
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
326-32
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
Molecular characterization of tissue-nonspecific alkaline phosphatase with an Ala to Thr substitution at position 116 associated with dominantly inherited hypophosphatasia.
pubmed:affiliation
Division of Oral Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't