Decreased rotational diffusion of band 3 in Melanesian ovalocytes from Papua, New Guinea

Melanesian ovalcytes from Papua New Guinea have an N-terminal extension of the band 3 polypeptide (Jones, G.L., Edmunson, H.M., Wesche, D., Saul, A. 1990. Biochim. Biophys. Acta 1096:33-40). The ovalocytes showed a threefold increase in shear elastic modulus as determined by micropipette aspiration measurements of membrane rigidity. Time-resolved phosphorescence anisotropy has been used to study the rotational freedom of band 3 in membranes prepared from ovalocytes. The ovalocytic polymorphism was found to be associated with a marked decrease in the rotational mobility of band 3. This may indicate participation of band 3 in large homoaggregates or in complexes with other proteins at the cytoplasmic surface. There was no morphological clustering of band 3 detectable by immunofluorescence microscopy.