Involved in the activation of the NAD-dependent methanol dehydrogenase (MDH). MDH activation by Act involves hydrolytic removal of the nicotinamide mononucleotide (NMN) moiety of the NAD cofactor, changing its ping-pong type of reaction mechanism into a ternary complex reaction mechanism. It requires the presence of magnesium ions and is also able to use ADP-ribose. kcat is 129 sec(-1) for hydrolase activity with ADP-ribose (at pH 9.5 and 50 degrees Celsius). kcat is 3.9 sec(-1) for hydrolase activity with NAD (at pH 9.5 and 50 degrees Celsius). Homodimer. Belongs to the Nudix hydrolase family.