FIG. 1.

Self-association of the tankyrase 1 SAM domain. (A) Superose 6 fractionation of MBP-SAM1. Peak fractions containing molecular weight markers are indicated: 2,000 kDa, dextran blue; 669 kDa, thyroglobulin; 232 kDa, catalase. Fraction numbers are shown below. (B and C) Transmission electron microscopy of uranyl acetate-stained MBP-SAM1 polymers. Arrows indicate SAM polymers. Samples shown in panel C were treated with proteinase K prior to deposition on the EM grid. Bar, 100 nm. (D) Histogram showing the length distribution of MBP-SAM1 rods. Mean (37 nm) and median (36 nm) lengths were calculated for 40 rods, but the shortest rods were probably underrepresented because they were difficult to distinguish from background.