Molecular epitopes of the ankyrin-spectrin interaction.

Isoforms of ankyrin and its binding partner spectrin are responsible for a number of interactions in a variety of human cells. Conflicting evidence, however, had identified two different, non-overlapping human erythroid ankyrin subdomains, Zu5 and 272, as the minimum binding region for beta-spectrin. Complementary studies on the ankyrin-binding domain of spectrin have been somewhat more conclusive yet have not presented binding in terms of well-phased, integral numbers of spectrin repeats.

Independent movement, dimerization and stability of tandem repeats of chicken brain alpha-spectrin.

Previous X-ray crystal structures have shown that linkers of five amino acid residues connecting pairs of chicken brain alpha-spectrin and human erythroid beta-spectrin repeats can undergo bending without losing their alpha-helical structure. To test whether bending at one linker can influence bending at an adjacent linker, the structures of two and three repeat fragments of chicken brain alpha-spectrin have been determined by X-ray crystallography. The structure of the three-repeat fragment clearly shows that bending at one linker can occur independently of bending at an adjacent linker.

Structural insights into the stability and flexibility of unusual erythroid spectrin repeats.

Erythroid spectrin, a major component of the cytoskeletal network of the red cell which contributes to both the stability and the elasticity of the red cell membrane, is composed of two subunits, alpha and beta, each formed by 16-20 tandem repeats. The properties of the repeats and their relative arrangement are thought to be key determinants of spectrin flexibility. Here we report a 2.

Stabilities of folding of clustered, two-repeat fragments of spectrin reveal a potential hinge in the human erythroid spectrin tetramer.

The large size of spectrin, the flexible protein promoting reversible deformation of red cells, has been an obstacle to elucidating the molecular mechanism of its function. By studying cloned fragments of the repeating unit domain, we have found a correspondence between positions of selected spectrin repeats in a tetramer with their stabilities of folding. Six fragments consisting of two spectrin repeats were selected for study primarily on the basis of the predicted secondary structures of their linker regions.