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

摘要: The large size of spectrin, the flexible protein promoting reversible deformation red cells, has been an obstacle to elucidating molecular mechanism its function. By studying cloned fragments repeating unit domain, we have found a correspondence between positions selected spectrin repeats in tetramer with their stabilities folding. Six consisting two were for study primarily on basis predicted secondary structures linker regions. Fragments putatively helical more stable urea- and heat-induced unfolding than those nonhelical linker. Two less stably folded fragments, human erythroid α-spectrin 13 14 (HEα13,14) β-spectrin 8 9 (HEβ8,9), are located opposite each other antiparallel dimers. At least partial these under physiological conditions indicates that they may serve as hinge. Also folded, fragment 4 5 (HEα4,5) lies site interaction at C- N-terminal ends β- α-spectrin, respectively, opposing dimer. More 1 2 (HEα1,2) 3 (HEα2,3), lie nearly dimers tetramer. These clusterings along similar folding relevance function, particularly well known flexibility.