TY - JOUR
T1 - Intracellular retention and degradation of tissue-nonspecific alkaline phosphatase with a Gly317→Asp substitution associated with lethal hypophosphatasia
AU - Fukushi, Mariko
AU - Amizuka, Norio
AU - Hoshi, Kazuto
AU - Ozawa, Hidehiro
AU - Kumagai, Hidetoshi
AU - Omura, Satoshi
AU - Misumi, Yoshio
AU - Ikehara, Yukio
AU - Oda, Kimimitsu
N1 - Funding Information:
This work is supported in part by Grants-in-Aid for Scienti®c Research from the Ministry of Education, Science and Culture of Japan.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1998/5/29
Y1 - 1998/5/29
N2 - One point mutation which converts glycine-317 to aspartate of tissue-nonspecific alkaline phosphatase (TNSALP) was reported to be associated with lethal hypophosphatasia. In order to define the molecular defect of TNSALP underlying the pathogenesis of hypophosphatasia, we have examined the biosynthesis of TNSALP with a Gly317→Asp substitution. When expressed in COS-1 cells, the mutant did not exhibit alkaline phosphatase activity at all, indicating that the replacement of glycine-317 with aspartate abolishes the catalytic activity of TNSALP. Pulse-chase experiments showed that the newly synthesized mutant failed to acquire Endo H-resistance and to reach the cell surface. Interestingly, this TNSALP mutant was found to form a disulfide-bonded high-molecular-mass aggregate and was rapidly degraded within the cell, though the mutant protein was modified by glycosylphosphatidylinositol (GPI). Lactacystin, an inhibitor of the proteasome, obstructed the degradation of the mutant protein, suggesting the involvement of proteasome as a part of quality control of TNSALP.
AB - One point mutation which converts glycine-317 to aspartate of tissue-nonspecific alkaline phosphatase (TNSALP) was reported to be associated with lethal hypophosphatasia. In order to define the molecular defect of TNSALP underlying the pathogenesis of hypophosphatasia, we have examined the biosynthesis of TNSALP with a Gly317→Asp substitution. When expressed in COS-1 cells, the mutant did not exhibit alkaline phosphatase activity at all, indicating that the replacement of glycine-317 with aspartate abolishes the catalytic activity of TNSALP. Pulse-chase experiments showed that the newly synthesized mutant failed to acquire Endo H-resistance and to reach the cell surface. Interestingly, this TNSALP mutant was found to form a disulfide-bonded high-molecular-mass aggregate and was rapidly degraded within the cell, though the mutant protein was modified by glycosylphosphatidylinositol (GPI). Lactacystin, an inhibitor of the proteasome, obstructed the degradation of the mutant protein, suggesting the involvement of proteasome as a part of quality control of TNSALP.
UR - http://www.scopus.com/inward/record.url?scp=17544395958&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=17544395958&partnerID=8YFLogxK
U2 - 10.1006/bbrc.1998.8674
DO - 10.1006/bbrc.1998.8674
M3 - Article
C2 - 9618260
AN - SCOPUS:17544395958
SN - 0006-291X
VL - 246
SP - 613
EP - 618
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 3
ER -