FIG. 4.

TGIF-related proteins from Drosophila. (A) dTGIFa and dTGIFb protein products are almost identical at the primary amino acid level. The dTGIFa sequence is shown in full, with amino acids that are different in dTGIFb shown below (dots indicate identity). The homeodomain is shaded black, the +20 region is gray, and two regions with a high proportion of acidic residues are boxed. The arrowheads indicate the position of the extra exon. (B) dTGIFa and dTGIFb are expressed from an adjacent pair of genes. Coding exons are in black, noncoding exons are in gray, and an alternatively spliced exon, not present in the clones analyzed here, is striped (see text for details). (C) dTGIFa and dTGIFb are shown schematically, with the percent identity and similarity between the HD +20 and the regions amino and carboxyl terminal to it. The two acid regions are shown, together with the position of insertion of the extra exon. (D) The proportions of acidic (D+E [aspartic acid and glutamic acid]) and basic (R+K [arginine and lysine]) residues in each of the acidic regions are shown. Below is the proportion of acidic or basic residues in the inserted extra exon alone and in the acidic N region with the extra exon.