AE1 (anion exchanger 1) and protein 4.2 associate in a protein complex bridging the erythrocyte membrane and cytoskeleton; disruption of the complex results in unstable erythrocytes and HS (hereditary spherocytosis). Three HS mutations (E40K, G130R and P327R) in cdAE1 (the cytoplasmic domain of AE1) occur with deficiencies of protein 4.2. The interaction of wild-type AE1, AE1HS mutants, mdEA1 (the membrane domain of AE1), kAE1 (the kidney isoform of AE1) and AE1SAO (Southeast Asian ovalocytosis AE1) with protein 4.2 was examined in transfected HEK (human embryonic kidney)-293 cells. The HS mutants had wild-type expression levels and plasma-membrane localization. Protein 4.2 expression was not dependent on AE1. Protein 4.2 was localized throughout the cytoplasm and co-localized at the plasma membrane with the HS mutants mdAE1 and kAE1, but at the ER (endoplasmic reticulum) with AE1SAO. Pull-down assays revealed diminished levels of protein 4.2 associated with the HS mutants relative to AE1. The mdAE1 did not bind protein 4.2, whereas kAE1 and AE1SAO bound wild-type amounts of protein 4.2. A protein 4.2 fatty acylation mutant, G2A/C173A, had decreased plasma-membrane localization compared with wild-type protein 4.2, and co-expression with AE1 enhanced its plasma-membrane localization. Subcellular fractionation showed the majority of wild-type and G2A/C173A protein 4.2 was associated with the cytoskeleton of HEK-293 cells. The present study shows that cytoplasmic HS mutants cause impaired binding of protein 4.2 to AE1, leaving protein 4.2 susceptible to loss during erythrocyte development.
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Research Article|
December 22 2010
Protein 4.2 interaction with hereditary spherocytosis mutants of the cytoplasmic domain of human anion exchanger 1
Susan P. Bustos;
Susan P. Bustos
*Department of Biochemistry, University of Toronto, Toronto, ON, Canada, M5S 1A8
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Reinhart A. F. Reithmeier
Reinhart A. F. Reithmeier
1
†Department of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8
1To whom correspondence should be addressed (email r.reithmeier@utoronto.ca).
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Publisher: Portland Press Ltd
Received:
August 25 2010
Revision Received:
October 28 2010
Accepted:
November 01 2010
Accepted Manuscript online:
November 01 2010
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2011 Biochemical Society
2011
Biochem J (2011) 433 (2): 313–322.
Article history
Received:
August 25 2010
Revision Received:
October 28 2010
Accepted:
November 01 2010
Accepted Manuscript online:
November 01 2010
Citation
Susan P. Bustos, Reinhart A. F. Reithmeier; Protein 4.2 interaction with hereditary spherocytosis mutants of the cytoplasmic domain of human anion exchanger 1. Biochem J 15 January 2011; 433 (2): 313–322. doi: https://doi.org/10.1042/BJ20101375
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