Fig. 1. Mutations in SdhA block SDH complex activity. (A) Schematic illustration of the electron transport chain complexes I-V. IMS, intermembrane space; IM, inner membrane; M, matrix; Ub, ubiquinone; CytC, cytochrome C. (B) Schematic of the SdhA protein structure denoting identified mutations. (C-E) Eye-specific mosaic third instar larval eye discs, visualizing the enzymatic activity of the SDH complex. (C) Wild type. Arrowheads demarcate the morphogenetic furrow. (D) SdhA mutant. (E) Wild-type disc, stained in the presence of the competitive inhibitor malonate.