InterPro: IPR017227 Nucleoside-triphosphatase, alveolata

This entry represents nucleoside-triphosphatase (EC:3.6.1.15) from parasites such as Toxoplasma gondii [1]. This enzyme acts as a heterotetramer. It is secreted and has been detected in host cell parasitophorous vacuoles, where it may perform an important processing step in the conversion of high energy nucleotides prior to uptake by the parasite. NTPAse-II has a specific activity 4.5-fold lower than NTPAse-I in hydrolysis of ATP. The primary difference between these isozymes lies in their ability to hydrolyse nucleoside triphosphate versus diphosphate substrates. While NTPAse-II hydrolyses ATP to ADP and ADP to AMP at almost the same rate, NTPAse-I hydrolyses ADP to AMP at a much slower rate (0.7% of the rate for ATP).