Figure 3.

A combination of long and short OPA1 isoforms increases mitochondrial fusion. (A) Coexpression of 1ΔS1 with short isoforms. The indicated constructs were expressed in OPA1-null cells and analyzed by Western blotting. (B) Functional complementation of 1ΔS1. OPA1-null cells were infected with retrovirus expressing splice forms 3, 5, 6, or 8. Each infected line along with an uninfected control was transfected with a control GFP vector or the GFP vector and OPA1-1ΔS1. (C) Processing of ΔS1 mutants. The indicated splice forms and mutants were expressed in OPA1-null cells. OPA1 was detected by Western blot analysis. Asterisks indicate novel cleavage products for 3ΔS1 and 5ΔS1. (D) Enhanced tubulation of mitochondria by ΔS1 mutants. The indicated OPA1 splice forms and mutants were expressed in OPA1-null cells. (B and D) Mitochondrial morphology was scored as in Fig. 1 C; error bars indicate the SD from triplicate experiments.