Mutations at residue 41 have species-specific effects on caspase activation.

<p>A. and B. Cleavage of the caspase 3 substrate Ac-DEVD-AMC was monitored in A. mouse WEHI164 (100 μg) and B. human U937 (100 μg) cytosols with the addition of 0 nM, 25 nM, 50 nM or 100 nM mouse somatic WT (white bars) or G41S (black bars) cytochrome <i>c</i> at pH 7.25. All reactions contained 1 mM dATP. Data are presented as mean ± SD (n = 3). *<i>P</i> < 0.01, **<i>P</i> < 0.001 compared to WT. C. Cleavage of the caspase 3 substrate Ac-DEVD-AMC was monitored in Xenopus cytosolic extracts (2 μg) with the addition of 100 nM human cytochrome <i>c</i> without (white bars) or with (black bars) the addition of human Apaf-1. Data are presented as mean ± SD (n = 3). *p < 0.01, **p < 0.001 compared to without human Apaf-1. Progress curves are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130292#pone.0130292.s002" target="_blank">S2B–S2D Fig</a>).