Total absence of protein 4.2 and partial deficiency of band 3 in hereditary spherocytosis

Abstract

Unlike previously reported cases with total protein 4.2 deficiency due to mutations in the EPB42 gene, we describe a total deficiency in protein 4.2 with normal EPB42 alleles. Hereditary spherocytosis (HS) was observed in a Japanese woman (unsplenectomized) and her daughter (splenectomized). The mother showed a partial deficiency in band 3 and a proportional reduction in protein 4.2. She was heterozygous for a novel allele of the EPB3 gene, allele Okinawa, which contains the two mutations that define the Memphis II polymorphism (K56E, AAG → GAG, and P854L, CCG → CTG) and, additionally, the mutation: G714R, GGG → AGG, located in a highly conserved position of transmembrane segment 9. The latter change was responsible for HS. In trans to allele Okinawa, the daughter displayed allele Fukuoka: G130R, GGA → AGA, an allele known to alter the binding of protein 4.2 to band 3. The daughter presented with a more pronounced decrease of band 3, and lacked protein 4.2, resulting in aggravated haemolytic features. Although the father was not available for study, heterozygosity for allele Fukuoka has been documented in another individual who showed no clinical or haematological signs, and a normal content of band 3. We suggest that band 3 Okinawa binds virtually all the protein 4.2 in red cell precursors, band 3 Fukuoka being unable to do so, and that the impossibility of band 3 Okinawa incorporation into the membrane leads to degradation of the band 3 Okinawa protein 4.2 complex. In contrast, band 3 Fukuoka, free of bound protein 4.2, could then incorporate normally into the bilayer. Thus, protein 4.2 would not appear in the daughter's red cell membrane.

Structure, Function, and Trafficking of SLC4 and SLC26 Anion Transporters

“…Prague V ( Jarolim et al, 1996) C479W R808C/H Jablonec, Nara ( Jarolim et al, 1996;Kanzaki et al, 1997;Quilty & Reithmeier, 2000) the BLM. Unlike AE1 in red cells, kAE1 is subject to endocytosis and turnover (Cordat, unpublished;Williamson, Brown, Mawby, & Toye, 2008).…”

Homozygous missense mutation (band 3 Fukuoka: G130R): a mild form of hereditary spherocytosis with near‐normal band 3 content and minimal changes of membrane ultrastructure despite moderate protein 4.2 deficiency

“…Membrane proteins were studied using sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS‐PAGE) by the methods of Fairbanks et al (1971 ) and Laemmli (1970) with Coomassie blue staining, and were scanned by Protein+DNA Image Ware Systems (PDI‐Toyobo Co., Tokyo, Japan). Western blotting was performed based on anti‐human P4.2 rabbit polyclonal IgG antibody ( Kanzaki et al , 1997a ). The contents of each membrane protein fraction were determined on SDS‐PAGE gels densitometrically and were expressed as relative amounts of the areas based on the O.D.…”

“…Reverse transcription (RT) was carried out using random hexamers. Band 3 cDNA was amplified by the polymerase chain reaction (PCR) essentially as described by Kanzaki et al (1997a , b). Five PCR pairs of primers were used to cover the entire band 3 cDNA coding sequence (from nucleotide (nt) −148 upstream from the ATG initiation codon to nt 2815).…”

Defects in Erythrocyte Membrane Skeletal Architecture

“…Mutations in the cytoplasmic domain of band 3 can interfere with its binding to other MS proteins, resulting in a functional defect. An amino acid substitution (G130A) in the cytoplasmic domain in band 3 Fukuoka possibly affects protein 4.2 binding (Kanzaki et al 1997 ). HS due to band 3 is inherited dominantly and is generally milder than HS caused by ankyrin or spectrin mutations.…”