Overall structure and representative electron density from MAD phasing of the MtSK•MgADP complex. MtSK contains eight alpha helices (blue ribbons), five beta strands (yellow arrows), and two 3₁₀ helices (blue ribbons) in three domains: LID, CORE, and SB. The ADP and HEPES molecules are shown as ball-and-stick models with atomic color scheme (C, black; N, blue; O, red; S, yellow; and P, purple) and the Mg²⁺ and Pt²⁺ ions are shown as bigger purple spheres. The initial electron density from MAD phasing is illustrated as green nets and contoured at the level of 1.0 sigma for Mg²⁺, Pt²⁺, ADP, HEPES, and Arg117 (Gu, Reshetnikova, Li, Wu, Yan, Singh, and Ji, J. Mol. Biol. 2002; 319:779-789. Abstract).