Absence of CD47 in protein 4.2-deficient hereditary spherocytosis in man: an interaction between the Rh complex and the band 3 complex.
We present data on a patient of South Asian origin with recessive hereditary spherocytosis (HS) due to absence of protein 4.2 [4.2 (-) HS]. Protein 4.2 cDNA sequence analysis showed the presence of a novel 41-bp frameshift deletion that predicts a truncated peptide designated protein 4.2 Hammersmith. Quantitative reverse transcription-polymerase chain reaction indicated that the mutant mRNA was unstable. Sequencing of protein 4.2 genomic DNA revealed that the deletion stems from aberrant splicing. The proband was homozygous for a G>T substitution at position 1747 (cDNA numbering) that activates a cryptic acceptor splice site within exon 11 of the protein 4.2 gene (EPB42). The proband's mother was found to be heterozygous for this substitution. Unlike protein 4.2 null mice, the proband's red cells showed no evidence for abnormal cation permeability. Quantitation of red cell membrane proteins was carried out by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Western blotting, and flow cytometric measurement. CD47, a protein associated with the Rh complex, was markedly reduced to about 1% (in the proband) and 65% (in the mother) that found in healthy controls. The Rh-associated glycoprotein migrated with a higher than normal apparent molecular weight on SDS-PAGE. There was no obvious reduction in Rh polypeptides. These observations indicate that protein 4.2 and CD47 interact in the human red cell membrane. They provide further evidence for an association between the band 3 complex (band 3, ankyrin, protein 4.2, glycophorin A) and the Rh complex (Rh-associated glycoprotein, Rh polypeptides, glycophorin B, CD47, LW) and define a point of attachment between the Rh complex and the red cell cytoskeleton.
Bruce
Lesley J
LJ
Department of Biochemistry, University of Bristol, and International Blood Group Reference Laboratory, Bristol, United Kingdom.
Ghosh
Sandip
S
King
May Jean
MJ
Layton
D Mark
DM
Mawby
William J
WJ
Stewart
Gordon W
GW
Oldenborg
Per-Arne
PA
Delaunay
Jean
J
Tanner
Michael J A
MJ
D000328:Adult; D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism; D017487:Ankyrins / Q000378:metabolism; D015703:Antigens, CD / Q000235:genetics* / Q000378:metabolism; D001798:Blood Proteins / Q000172:deficiency / Q000235:genetics*; D051928:CD47 Antigen; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D003598:Cytoskeletal Proteins; D004910:Erythrocyte Membrane / Q000378:metabolism; D005091:Exons; D006021:Glycophorins / Q000378:metabolism; D006801:Humans; D008297:Male; D008565:Membrane Proteins; D012204:Rh-Hr Blood-Group System / Q000378:metabolism; D013103:Spherocytosis, Hereditary / Q000235:genetics / Q000378:metabolism
D001457:Anion Exchange Protein 1, Erythrocyte; D017487:Ankyrins; D015703:Antigens, CD; D001798:Blood Proteins; D051928:CD47 Antigen; C497894:CD47 protein, human; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D006021:Glycophorins; D008565:Membrane Proteins; D012204:Rh-Hr Blood-Group System; C044791:erythrocyte membrane band 4.2 protein