Figure 6.

Loss of SRT2 affects coupling of ATP synthesis to mitochondrial respiration and ADP uptake into mitochondria. A, TCA cycle-dependent respiration (pyruvate, malate) in isolated mitochondria of wild-type (WT) and srt2-1 seedlings. Respiratory activities were measured in state II and state III (100 µm ADP) mitochondria (n = 6, + se). B, Respiratory control ratios calculated from respiratory activities before and after ADP addition (n = 6, ± se). C, Integrity of the outer membrane calculated by the latency of cytochrome c oxidation before and after addition of Triton-X100 to mitochondria (n = 6, ± se). D, ATP to ADP ratios in srt2-1 seedlings compared with the wild type (n = 5, ± se). E, ATP contents in srt2-1 seedlings compared with the wild type (n = 5, ± se). F, ADP contents in srt2-1 seedlings compared with the wild type (n = 5, ± se). G, Time course of ¹⁴C-ADP uptake into isolated mitochondria of wild-type (white bars) and srt2-1 seedlings (black bars; n = 5, + se). Asterisks indicate significant difference (*P < 0.05, **P < 0.01, ***P < 0.001, Student’s t test).