Figure 3.

(a) Sequence alignment of Human and Sea Urchin PC2-EF and the suPC2-EF-z-x1 mutant. Relative positions of the structural helices for hPC2-EF are shown above the aligned sequences, with the numbering for the suPC2-EF-x-z1 construct shown at the bottom of the alignment. Sea Urchin constructs are preceded by the N-terminal His-tag sequence MGSSHHHHHHSSGLVPRGSHMASGKINFKR and the Human construct by MGSSHHHHHHSSGLVPRGSHM. (b) Overlaid two-dimensional ¹H-¹⁵N HSQC NMR spectra of calcium-saturated ¹⁵N hPC2-EF (green traces), ¹⁵N suPC2-EF (red traces), and ¹⁵N suPC2-EF-x-z1 (blue traces) proteins in pH 7.4, 25 mM TRIS, 150 mM KCl buffer with 1 mM TCEP and 10 mM Ca²⁺ at 25°C.