Fourth International Symposium on Neuroacanthocytosis

Abstracts from the Fourth International Symposium on Neuroacanthocytosis

July 1-2, 2008
London and Oxford

Chairs: Prof. Kailash Bhatia, MD, FRCP, Institute of Neurology, University College London; Prof. Anthony P. Monaco, MD, PhD, Wellcome Trust Centre for Human Genetics, University of Oxford

Organizers: Antonio Velayos-Baeza, PhD; Susanne Schneider, MD; Glenn Irvine

6-2 Protein interactions in the erythrocyte membrane
N. Mohandas, and X. An
Kimball Research Institute, New York Blood Center, New York, NY, USA

Erythrocyte membrane is a composite structure in which a plasma membrane envelope composed of cholesterol and phospholipids is anchored to a two dimensional elastic network of skeletal proteins through tethering sites on cytoplasmic domains of a number of transmembrane proteins embedded in the lipid bilayer. Direct interaction of several skeletal proteins with the anionic phospholipids provides additional tethering of the skeletal network with lipid bilayer. More than 50 transmembrane proteins of varying abundance ranging from a few hundred to approximately a million copies per red cell have been identified. A large fraction of these transmembrane proteins, approximately 25, specify the various blood groups. Transmembrane proteins exhibit diverse functional heterogeneity serving as cation, water and urea transporters, as adhesive proteins involved in interactions of red cells with other blood cells and endothelial cells, in cell signaling events and some with yet to be defined. Of direct relevance to structural integrity of the membrane are membrane proteins, band 3, glycophorin C and RhAG that link the bilayer to the spectrin based membrane skeleton. Band 3 and RhAG link the bilyer to the membrane skeleton through the interaction of their cytoplasmic domains with ankyrin while glycophorin C links through its interaction with protein 4.1R. We have recently documented that XK, the membrane protein deficient in acanthocytosis, binds to both 4.1R and spectrin. We speculate that this newly identified skeletal linkage of XK may play a role in shape abnormalities of acanthocytosis.