Human GAPDH Recombinant Protein. GAPDH (Glyceraldehyde-3-phosphate dehydrogenase) is a catalytic enzyme commonly known to be involved in glycolysis. GAPDH exists as a tetramer of identical 37-kDa subunits and catalyzes the reversible reduction of 1,3-bisphosphoglycerate to glyceraldehyde 3-phosphophate in the presence of NADPH. Apart from playing a key role in glycolysis, GAPDH is ubiquitously expressed and displays other activities unrelated to its glycolytic function. GAPDH is reported to be involved in the processes of DNA replication, DNA repair, nuclear RNA export, membrane fusion and microtubule bundling. Studies provide evidence of GAPDH playing an essential part in gene expression observed in apoptosis and as part of the cellular ph