TY - JOUR
T1 - Cubilin P1297L mutation associated with hereditary megaloblastic anemia 1 causes impaired recognition of intrinsic factor-vitamin B12 by cubilin
AU - Kristiansen, Mette
AU - Aminoff, Maria
AU - Jacobsen, Christian
AU - De La Chapelle, Albert
AU - Krahe, Ralf
AU - Verroust, Pierre J.
AU - Moestrup, Søren K.
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2000/7/15
Y1 - 2000/7/15
N2 - Megaloblastic anemia 1 (MGA1) is an autosomal recessive disorder caused by the selective intestinal malabsorption of intrinsic factor (IF) and vitamin B12/cobalamin (Cbl) in complex. Most Finnish patients with MGA1 carry the disease-specific P1297L mutation (FM1) in the IF-B12 receptor, cubilin. By site-directed mutagenesis, mammalian expression, and functional comparison of the purified wild-type and FM1 mutant forms of the IF-Cbl- binding cubilin region (CUB domains 5-8, amino acid 928-1386), we have investigated the functional implications of the P1297L mutation. Surface plasmon resonance analysis revealed that the P1297L substitution specifically increases the K(d) for IF-Cbl binding several-fold, largely by decreasing the association rate constant. In agreement with the binding data, the wild-type protein, but not the FM1 mutant protein, potently inhibits 37°C uptake of iodine 125-IF-Cbl in cubilin-expressing epithelial cells. In conclusion, the data presented show a substantial loss in affinity of the FM1 mutant form of the IF-Cbl binding region of cubilin. This now explains the malabsorption of Cbl and Cbl-dependent anemia in MGA1 patients with the FM1 mutation. (C) 2000 by The American Society of Hematology.
AB - Megaloblastic anemia 1 (MGA1) is an autosomal recessive disorder caused by the selective intestinal malabsorption of intrinsic factor (IF) and vitamin B12/cobalamin (Cbl) in complex. Most Finnish patients with MGA1 carry the disease-specific P1297L mutation (FM1) in the IF-B12 receptor, cubilin. By site-directed mutagenesis, mammalian expression, and functional comparison of the purified wild-type and FM1 mutant forms of the IF-Cbl- binding cubilin region (CUB domains 5-8, amino acid 928-1386), we have investigated the functional implications of the P1297L mutation. Surface plasmon resonance analysis revealed that the P1297L substitution specifically increases the K(d) for IF-Cbl binding several-fold, largely by decreasing the association rate constant. In agreement with the binding data, the wild-type protein, but not the FM1 mutant protein, potently inhibits 37°C uptake of iodine 125-IF-Cbl in cubilin-expressing epithelial cells. In conclusion, the data presented show a substantial loss in affinity of the FM1 mutant form of the IF-Cbl binding region of cubilin. This now explains the malabsorption of Cbl and Cbl-dependent anemia in MGA1 patients with the FM1 mutation. (C) 2000 by The American Society of Hematology.
UR - http://www.scopus.com/inward/record.url?scp=0034661941&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034661941&partnerID=8YFLogxK
U2 - 10.1182/blood.v96.2.405.014k16_405_409
DO - 10.1182/blood.v96.2.405.014k16_405_409
M3 - Article
C2 - 10887099
AN - SCOPUS:0034661941
SN - 0006-4971
VL - 96
SP - 405
EP - 409
JO - Blood
JF - Blood
IS - 2
ER -