Group I intron location along the protein sequence (panel A) and in the structure of the DNA polymerase I (panel B). Panel A shows conservation profile of DNA polymerase I (see figure one for details). Panel B shows the structure of the DNA polymerase I (Klenow Fragment) from Escherichia coli (PDB ID: 1KLN) colored according to site conservation. The arrow indicates intron insertion site, of the intron found in homologous protein in Bacillus subtilis phage SPO1, which is between Asn675 and Leu676 (space-filled model).
Swithers et al. BMC Evolutionary Biology 2009 9:303 doi:10.1186/1471-2148-9-303