Long-range crosslinks unique to the L260P tetramer. (A) Schematic representation of 6 key crosslinks (black lines in right half of model; these crosslinks are repeated as gray lines in the left half of the model, which is a mirror image of the right half) unique to L260P tetramers (Table 2). The colored region indicates repeats used for modeling structural changes required to accommodate distance constraints imposed by L260P-specific crosslinks. (B) A structural model of the colored region of WT mini-spectrin. Locations of 3 L260P tetramer-specific crosslinks (Table 2; crosslinks 1-3) and the distances between the crosslinked residues in the WT structure are highlighted. Crosslinked side chains are presented using spheres (blue, K; red, D or E). (C-E) The light cyan WT tetramer model (B) is superimposed on alternative L260P structures. (C) The model shown in orange was derived by applying the distance constraint defined by crosslink 1 in panel B (residues 508-364). The black sphere shows the location of the L260P mutation. (D) The model shown in blue was derived by applying the distance constraint defined by crosslink 2 in panel B (residues 265-466). (E) The model shown in red was derived by first applying crosslink 2 followed by crosslinks 1 and 3. (F) The distances between α-carbons for 6 key L260P tetramer-specific crosslinked residues on the models are shown in panels B-E. The horizontal line at 12 Å defines the expected maximum distance between α-carbons of residues capable of being crosslinked by a zero-length crosslinking reagent.