A reversible enzyme with a similar function, pyruvate phosphate dikinase (PPDK), is found in some bacteria and has been transferred to a number of anaerobic eukaryote groups (for example, Streblomastix, Giardia, Entamoeba, and Trichomonas), it seems via horizontal gene transfer on two or more occasions. In some cases, the same organism will have both pyruvate kinase and PPDK.[25]