Involved in chlorophyll synthesis and chloroplast protection against oxidative damage. ATP + NAD(+) = ADP + H(+) + NADP(+) Measured at pH 7.9 and 25 degrees Celsius for all experiments. Optimum pH is 7.9 at 25 degrees Celsius. A number of isoforms are produced. According to EST sequences. Expressed in leaves. Expressed during development from young seedlings to flowering plants. Belongs to the NAD kinase family.