Evidence that Wra and Wrb are antithetical

Functional factors in the red cell membrane: interactions between the membrane and its underlying skeleton

Recent studies involving two abnormal red cell phenotypes (South-east Asian ovalocytosis and Leach phenotype) provide novel information concerning the nature and significance of interactions of both the anion transport protein AE-1 (syn. band 3) and Glycophorins C and D with the underlying skeleton. The location of Wra and Dia blood group antigens to mutations on AE-1 at residues 658 and 854 respectively, together with the availability of monoclonal antibodies recognising epitopes dependent upon the integrity of the third extracellular loop of AE-1, have allowed us to study the organisation of the membrane domain of the mutant AE-1 found in South-east Asian ovalocytes (AE-1 SAO). The results suggest that the organisation of the whole membrane domain of AE-1 SAO is abnormal and that the organisation of other integral membrane proteins like those involved in expression of Rh blood group antigens may also be affected. Increased homo- and hetero-associations involving AE-1 SAO and other integral proteins may in turn result in reduced membrane flexibility. Purified protein 4.1 binds with 50-fold higher affinity to protein 4.1 depleted normal red cell membranes than to protein 4.1 depleted red cell membranes of Leach phenotype which lack Glycophorin C (GPC) and Glycophorin D (GPD). Experiments using purified protein 4.1 and p55 together with synthetic peptides corresponding to different regions of the cytoplasmic domain of Glycophorins C and D (GPC/D) demonstrate that protein 4.1 interacts directly with GPC through residues 82-98. They also show that p55 binds to GPC through residues 112-128. Since p55 also binds directly to protein 4.1 it is clear that protein 4.1 can bind to GPC through two different sites either directly through residues 82-98 or indirectly through p55. These results show that GPC and GPD provide major attachment sites for the red cell skeleton via protein 4.1 and that p55 is part of this complex.

Comparative immunochemical analysis of Wra and Wrb red cell antigens

This paper describes immunoblotting and immunoprecipitation studies using monoclonal anti-Wra and anti-Wrb antibodies to investigate the nature of the low-incidence blood group antigen, Wra and its high-incidence allelic antigen Wrb. No membrane components were identified by the immunoblotting experiments. Immunoprecipitation studies confirmed that the Wrb antigen involves both glycophorin A and band 3. The monoclonal anti-Wra, BGU1-WR, failed to immunoprecipitate these or any othe red cell membrane component. The significance of these findings is discussed.