Figure 1.

SF3B1 ULM5 (residues 333–351) is a relevant, high-affinity ligand for the U2AF2 UHM.A, schematic diagram of the SF3B1 (yellow)–U2AF2 (navy) complex at the 3′ splice site (gray). The sequence of the ULM5 region is expanded above, with the ULM consensus marked in color for basic residues (blue), acidic residues (red), or tryptophan (yellow). Boundaries of regions used for isothermal titration calorimetry are indicated by double-headed arrows. B, bar graph of the average apparent binding affinities (K_A) and standard deviations of three isothermal titration calorimetry experiments. The residue ranges of the SF3B1 fragment in the sample cell are given on the x-axis and the U2AF2 residues are listed below. SF3B6 (also called p14a) is included in the first experiment of the graph (taupe). Values reproduced from Thickman et al (2006) J. Mol. Biol. v356:664 are marked by asterisks. The thermodynamic values and representative isotherms are given in Table S1 and Fig. S1. Significance was assessed by unpaired t tests with Welch’s correction implemented in GraphPad Prism, here and for all figures: n.s., not significant; ∗p < 0.05; ∗∗p < 0.005; ∗∗∗p < 0.0005.