Nicotinamide adenine dinucleotide
Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are two important coenzymes found in cells. NADH is the reduced form of NAD.
NAD is used extensively in glycolysis and the citric acid cycle of cellular respiration. It forms NADP with the addition of a phosphate group (much as ADP forms ATP). NADP is produced in the preliminary cycles of photosynthesis, and is used in the later Calvin cycle of photosynthesis. It is used in many other anabolic reactions in various organisms, as well.