Figure 2.

Structure of the SKIP^WD-KLC2^TPR cargo complex. (A,B) Cartoon representations of the SKIP^WD motif (displayed as stick model in green) bound to KLC2^TPR domain (orange cartoon) in two orthogonal orientations. Simulated annealing (F_o-F_c) omit map for the W-acidic cargo motif is contoured at the 3σ level. Individual TPR repeats composed by helix-turn-helix elements (I and E for internal and external, respectively) are highlighted in A. A non-TPR helix (αN) is between TPR5 and TPR6. Panel B also shows the apo KLC2^TPR structure (grey transparent cartoon) with an orange arrow indicating the movement of the TPR2-3 region with respect to the common TPR4-6 reference frame. (C) Electrostatic potential surface representation of KLC2^TPR with its SKIP^WD-bound cargo. Positive and negative potential is shown in blue and red, respectively. Cargo recognition is achieved by a combination of charge complementarity and sequence specificity.