Figure 2

The residue E221 of LETM1 is critical for Ca²⁺ transport.

(A) Sequence alignment of the presumed transmembrane helix. The conserved amino acids are highlighted in red. The amino acids that potentially participated in Ca²⁺ transport are designated with black stars. (B) Aequorin luminescence measurement. Quantification of mitochondrial Ca²⁺ peak amplitudes in empty vector, wild-type LETM1 and the mutants in HeLa cells after stimulation with 100 μM histamine. The data are expressed as the mean ± SEM and the mean values are from 5 independent experiments. **P < 0.01, *P < 0.05, n.s, not significant. (C) Western-blot of the expressed LETM1 wild-type and mutants. LETM1 was immunoblotted with anti-HA antibody. Full gel and blots were shown in Figure S4. (D) Rhod-2 dye fluorescence measurement. Responses of the mitochondrial Ca²⁺ in the HeLa cells after stimulation of 100 μM of histamine. Solid lines represent the mean values; shaded regions represent mean ± SEM.