Sequence alignment of Acanthamoeba castellanii Src kinase and its orthologs. (a) Domain architecture of human c-Src kinase. The two important regulatory phosphorylation sites (Y419 and Y530) are marked. (b) Putative Acanthamoeba Src kinase (AcSrc) sequence was aligned with Drosophila melanogaster c-Src (DmSrc), Caenorhabditis elegans Src (CeSrc), Ephydatia fluviatilis Src related protein (EfSrc), Monosiga brevicollis Src1 (MbSrc), Hydra vulgaris (HvSrc) and Homo sapiens cSrc (HsSrc). The SH3, SH2 and catalytic domain are indicated with yellow, blue and green bars above the sequence, respectively. Asterisk (*), colon (:) and period (.) marks the region of conserved, strongly similar and weakly similar residues, respectively. Whereas black diamond represents residues involve in ATP binding; black arrowheads represents residues form hydrogen bond with PP2, and black circles indicates the Y419 and Y530 phosphorylation sites in human cSrc, most of which are also conserved in AcSrc.