Volume 171, Issue 5 pp. 862-871
Research Paper

The human Kell blood group binds the erythroid 4.1R protein: new insights into the 4.1R-dependent red cell membrane complex

Slim Azouzi

Slim Azouzi

Institut National de la Transfusion Sanguine, Paris, France

Inserm, UMR_S1134, Paris, France

Université Paris Diderot, Sorbonne Paris Cité, Paris, France

Laboratory of Excellence GR-Ex, New York, NY, USA

These authors contributed equally to this work.Search for more papers by this author
Emmanuel Collec

Emmanuel Collec

Institut National de la Transfusion Sanguine, Paris, France

Inserm, UMR_S1134, Paris, France

Université Paris Diderot, Sorbonne Paris Cité, Paris, France

Laboratory of Excellence GR-Ex, New York, NY, USA

These authors contributed equally to this work.Search for more papers by this author
Narla Mohandas

Narla Mohandas

New York Blood Center, New York, NY, USA

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Xiuli An

Xiuli An

New York Blood Center, New York, NY, USA

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Yves Colin

Yves Colin

Institut National de la Transfusion Sanguine, Paris, France

Inserm, UMR_S1134, Paris, France

Université Paris Diderot, Sorbonne Paris Cité, Paris, France

Laboratory of Excellence GR-Ex, New York, NY, USA

These authors contributed equally to this work.Search for more papers by this author
Caroline Le Van Kim

Corresponding Author

Caroline Le Van Kim

Institut National de la Transfusion Sanguine, Paris, France

Inserm, UMR_S1134, Paris, France

Université Paris Diderot, Sorbonne Paris Cité, Paris, France

Laboratory of Excellence GR-Ex, New York, NY, USA

These authors contributed equally to this work.

Correspondence: Caroline Le Van Kim, UMR_S1134, Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015 Paris, France.

E-mail: [email protected]

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First published: 12 October 2015
Citations: 11

Summary

Protein 4.1R plays an important role in maintaining the mechanical properties of the erythrocyte membrane. We analysed the expression of Kell blood group protein in erythrocytes from a patient with hereditary elliptocytosis associated with complete 4.1R deficiency (4.1(−) HE). Flow cytometry and Western blot analyses revealed a severe reduction of Kell. In vitro pull down and co-immunoprecipitation experiments from erythrocyte membranes showed a direct interaction between Kell and 4.1R. Using different recombinant domains of 4.1R and the cytoplasmic domain of Kell, we demonstrated that the R46R motif in the juxta-membrane region of Kell binds to lobe B of the 4.1R FERM domain. We also observed that 4.1R deficiency is associated with a reduction of XK and DARC (also termed ACKR1) proteins, the absence of the glycosylated form of the urea transporter B and a slight decrease of band 3. The functional alteration of the 4.1(−) HE erythrocyte membranes was also determined by measuring various transport activities. We documented a slower rate of HCO3/Cl exchange, but normal water and ammonia transport across erythrocyte membrane in the absence of 4.1. These findings provide novel insights into the structural organization of blood group antigen proteins into the 4.1R complex of the human red cell membrane.

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