Involved in the regulation of the intracellular balance of NAD and NADP, and is a key enzyme in the biosynthesis of NADP. Catalyzes specifically the phosphorylation on 2'-hydroxyl of the adenosine moiety of NAD to yield NADP. ATP + NAD(+) = ADP + H(+) + NADP(+) Belongs to the NAD kinase family. Extended N-terminus.