Fig. 3. Mapping the lamin-binding regions in titin 1-551. (A) Schematic diagram of titin 1-551, showing locations of predicted Ig-fold domains (gray) and titin-specific domains M-is6 and M-is7. Bars numbered 1-6 represent the titin subfragments tested for binding to the pre-lamin A tail. (B) Autoradiograph showing ³⁵S-labeled titin fragments bound to His-tagged pre-lamin A tail (on Ni²⁺ beads). Corresponding unbound (supernatant, S) and bound (pellet, P) fractions (20% each) were resolved by SDS-PAGE and exposed to film. (C) Data from panel B are shown as the ratio of bound:unbound probe for ³⁵S-titin fragments 1-6. Bars indicate standard deviations from four independent experiments.