Fig. 1. Identification of point mutations in lethal alleles of Drosophila vha55. (A) Sample results from PCR-based SSCP gel, showing extra bands in mutants (arrows). C, control wild-type (Oregon R) genomic DNA; mutant strains are as described in the text. (B) Sequencing results. Point mutations and amino acid changes are indicated above the vha55 gene structure diagram. The four exons are labelled E1-E4; the introns are not to scale. The translated region is shown in black. Nucleotide numbers are relative to the Gadfly annotation for transcript A. Alignments for each of the mutated regions are shown: the mutated residue is underlined in the Drosophila sequence. The genes used are: D. melanogaster, vha55; H. sapiens, ATP6V1B2; S. cerevisiae, vma2; A. thaliana, At1g76030.