Sequence of the LD domain in various strains and species. (A) Comparison of D. melanogaster strains. Exon 15ext was sequenced in various strains, and the encoded protein was compared to the canonical sequence available on FlyBase. Shown are the klarMW and klarZ allele, the wild-type strain Tai255.1, as well as three mutagenized chromosomes from the Zuker collection (Z3-3772, Z3-1140, Z3-1711). Changes from the canonical sequence are indicated in red. The wild-type LD domain encompasses 114 amino acids. (B) Sequence variation in the LD domain across fly species. Candidate klar exons 15 and 15ext were identified in sixteen fly species based on sequence similarity to the corresponding D. melanogaster exons. Predicted protein sequences were aligned with Clustal2. * = position at which residues are absolutely conserved; : = position at which residues show similar chemical properties; . = partial conservation. Color scheme highlights chemically similar amino acids. A 26 aa stretch in exon 15 and a 46 aa stretch in exon 15ext are highly conserved. The red arrow indicates at which point the protein sequence of the klarMW allele diverges from the wild-type sequence; this allele deletes the entire 46 aa conserved region (amino acids 51-96) in exon 15ext. (C) Helical wheel diagram for amino acids 57-74 of the D. melanogaster LD domain. Potentially charged residues are represented in light blue; for uncharged residues, hydrophobicity is indicated by a scale from red (most hydrophilic) to green (most hydrophobic). This amino-acid sequence is compatible with an amphipathic helix structure. A similar pattern of hydrophobicity is conserved across all seventeen species shown in (B).