Figure 4

Alternative splicing of D. melanogaster MsrA and MsrB genes. (A) Genomic structures of Drosophila MsrA and MsrB genes. Translation initiation sites are indicated by arrows. Boxes indicate exons, which are numbered. Upper images show organization of the cytosolic forms of MsrA (left) and MsrB (right), respectively, and lower images of the mitochondrial forms of these proteins. (B) N-terminal amino acid sequences of alternatively spliced variants of MsrA and MsrB. Arrow indicates initiation of translation of cytosolic MsrB. However, this methionine is an internal residue in the mitochondrial MsrB form. Mitochondrial signal peptides are shown in italics.