African trypanosomes possess high levels of alanine aminotransferase (EC ), although the function of their activity remains enigmatic, espe-cially in slender bloodstream forms where the metabolism of ketoacids does not occur. Therefore, the gene for alanine aminotransferase enzyme inTry-panosoma brucei(TbAAT) was characterized and its function assessed using a combination of RNA interference and gene knockout approaches.