Structure-based dynamic arrays in regulatory domains of sodium-calcium exchanger (NCX) isoforms

Figures

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  Figure 1. Structure and alternative splicing of NCX-CBD12 isoforms. The models of NCX1-CBD12-AD (brain splice variant) (A), NCX2-CBD12 (B), and NCX3-CBD12-AC (C) are presented as cartoons. CBD1 is in orange and CBD2 is in red. Four Ca2+ ions bound to CBD1 are presented as green spheres. The alternative splicing schemes of NCX1 (A), NCX2 (B), and NCX3 (C) are presented below the models.

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  Figure 2. Ab-initio modelling of CBD12 from NCX2 and NCX3. (A,D,G) Experimental SAXS curves of CBD12 from NCX2 (A), NCX3-AC (D), and NCX3-B (G) in the presence (red) and absence (black) of Ca2+. (B,E,H) Paired-distance distribution functions of CBD12 from NCX2 (B), NCX3-AC (E), and NCX3-B (H) in the presence (red) and absence (black) of Ca2+ as determined using GNOM. (C,F,I) Ab-initio model of CBD12 from NCX2 (C), NCX3-C (F), and NCX3-B (I) in solution in the presence of Ca2+. The homology model of CBD12 was fit into the molecular envelope using SUPCOMB. CBD1 and CBD2 are presented as orange and red cartoons, respectively.

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  Figure 3. EOM analyses of CBD12 from NCX2 and NCX3. (A,D,G) Experimental SAXS curve and EOM fit of CBD12 from NCX2 (A), NCX3-AC (D), and NCX3-B (G) in the presence of Ca2+. (B,E,H) Random Rg pool (black line) and EOM-selected ensemble (red line) distributions of NCX2-CBD12 (B), NCX3-CBD12-AC (E), and NCX3-CBD12-B (H). (C,F,I) Random Dmax pool (black line) and EOM-selected ensemble (red line) distributions of NCX2-CBD12 (C), NCX3-CBD12-AC (F), and NCX3-CBD12-B (I).

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  Figure 4. Effect of alternative splicing on the conformational dynamics of NCX3-CBD12. Deuterium uptake differences between NCX3-AC and NCX3-B in the apo form (A) or in the Ca2+-bound form (B) are color-coded onto the model of NCX3-AC. Regions with similar deuterium uptake are yellow, regions with higher deuterium uptake in NCX3-AC are red, and regions with higher deuterium uptake in NCX3-B are blue. The alternative splicing region is in green and regions not covered by the detected peptic peptides are in gray. The uptake plots of the indicated peptic peptides are presented. Error bars represent SEM, * indicated p < 0.05 as analyzed by t-test.

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  Figure 5. Effect of Ca2+ binding on NCX2-CBD12 and NCX3-CBD12 dynamics. Deuterium uptake differences between the Ca2+-bound form and the apo form as a function of residue at different time points as indicated are plotted for NCX2-CBD12 (A), NCX3-CBD12-AC (B), and NCX3-CBD12-B (C). The data are also qualitatively depicted on the models of NCX2-CBD12 (A), NCX3-CBD12-AC (B), and NCX3-CBD12-B (C). Regions with lower deuterium uptake in the Ca2+-bound form are in blue, regions with similar deuterium uptake in the Ca2+-bound form and apo form are in yellow, and regions not covered by the detected peptic peptides are in gray.