Increased function of the A88E and L148H BTHS mutants in the absence of the i-AAA protease. (A and B) The relative abundance of MLCL (A) and CL (B) was determined for each strain and is expressed as a percentage of the total phospholipid in each strain (means ± SEM; n = 5). Student t tests were performed for each construct as expressed in Δtaz1 and Δtaz1Δyme1 yeast strains with significant differences indicated. (C) Comparison of CL in Δtaz1 and Δtaz1Δyme1 yeast strains transformed as indicated. The mass content of each molecular form of CL (acyl chain composition indicated) was determined by multidimensional mass spectrometric array analyses by comparison of the peak intensity of each individual ion to that of the internal standard (means ± SEM; n = 3). The four BTHS mutants being characterized in the present study are shown in red. m/z, mass to charge ratio.