Identification of the putative DNA Ligase I in Drosophila and its potential PBD. BLAST search of the D. melanogaster genome and EST database with DNA Ligase I (from different species) identified three similar sequences CG5602, CG17227 and CG12176. (A) Each of the putative DNA ligase protein sequences identified in Drosophila was aligned pairwise with HsDNA Lig I. The percentage identity is indicated at the right. (B) Table showing percentage identity obtained from pairwise alignment of the three putative DNA ligase homologues in Drosophila with each of HsDNA Ligase I, III and IV. (C) Phylogenetic tree from the comparison of HsDNA ligases and the Drosophila homologues created in Lasergene program. Scale represents amino acid substitution). (D) Structure of DmDNA Lig I gene and predicted protein. The gene structure is illustrated at the top; numbers indicate nucleotide positions; white boxes represent introns. A region in the 5th exon (marked gray) was found to be absent in the cDNA clone. This region was not detected as an intron using algorithms to detect introns. In the middle the LD41868 cDNA clone obtained from ResGen. Translational start is shown by arrow and the protein produced from this cDNA clone is illustrated at the bottom. (E) PBD-like sequences identified in DmDNA Lig I protein. Asterisk indicates the beginning or end of the protein sequence. Other features as in Figure 1B.