Bis(5'-nucleosyl)-tetraphosphatase [asymmetrical] (EC 3.6.1.17) (Diadenosine 5',5'''-P1,P4-tetraphosphate asymmetrical hydrolase) (Diadenosine tetraphosphatase) (Ap4A hydrolase) (Ap4Aase) (Nucleoside diphosphate-linked moiety X motif 2) (Nudix motif 2); Asymmetrically hydrolyzes Ap4A to yield AMP and ATP. Plays a major role in maintaining homeostasis (147 aa)