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XB-ART-37062
Blood June 1, 2008; 111 (11): 5380-9.

Band 3 Courcouronnes (Ser667Phe): a trafficking mutant differentially rescued by wild-type band 3 and glycophorin A.

Toye AM , Williamson RC , Khanfar M , Bader-Meunier B , Cynober T , Thibault M , Tchernia G , Déchaux M , Delaunay J , Bruce LJ .


Abstract
We describe a mutation in human erythrocyte band 3 (anion exchanger 1; SLC4A1) causing both hereditary spherocytosis and distal renal tubular acidosis. The proband developed a transfusion-dependent, hemolytic anemia following birth. Immunoblotting showed band 3 was reduced to approximately 35% of wildtype; other proteins of the band 3/Rh macrocomplex were also reduced. DNA sequence analysis revealed a novel homozygous mutation, c.2000C>T, leading to the amino acid substitution Ser667Phe. The parents were heterozygous for the same mutation. Sulfate influx in the patient''s erythrocytes was approximately 40% wild type. The mutant band 3 produced very little chloride influx when expressed in Xenopus oocytes. Influx was partially rescued by coexpression of glycophorin A and also rescued by coexpression of wild-type band 3. At 2 years of age, an ammonium chloride challenge showed the child has incomplete distal renal tubular acidosis (dRTA). Stable expression of mutant kidney band 3 in both nonpolarized and polarized Madin-Darby canine kidney cells showed that most of the mutant protein was retained in the endoplasmic reticulum. Overall our results suggest that the Ser667Phe does not affect the anion transport function of band 3, but causes a trafficking defect in both erythrocytes and kidney cells.

PubMed ID: 18174378
PMC ID: PMC2605348
Article link: Blood
Grant support: [+]
Genes referenced: actl6a aqp1 canx cd44 epb41 erg gypc igf2bp3 isyna1 rhag slc4a1 tgoln2


Article Images: [+] show captions
References [+] :
Bruce, Band 3 mutations, renal tubular acidosis and South-East Asian ovalocytosis in Malaysia and Papua New Guinea: loss of up to 95% band 3 transport in red cells. 2001, Pubmed, Xenbase


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