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N-terminal NAD(P)-binding domain of type I glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and similar proteins GAPDH plays an important role in glycolysis and gluconeogenesis by reversibly catalyzing the oxidation and phosphorylation of D-glyceraldehyde-3-phosphate to 1,3-diphospho-glycerate. It has been implicated in varied activities including regulating mRNA stability, the regulation of gene expression, induction of apoptosis, intracellular membrane trafficking, iron uptake and transport (via secreted GAPDH), heme metabolism, the maintenance of genomic integrity, and nuclear tRNA export. GAPDH contains an N-terminal NAD(P)-binding domain and a C-terminal catalytic domain. The N-terminal NAD(P)-binding domain contains a Rossmann fold which combines with the catalytic cysteine-containing C-terminus to form a catalytic cleft. Phosphatidyl-serine, RNA, and glutathione binding sites have been identified in the N-terminus. Different forms of GAPDH exist which utilize NAD (EC 1.2.1.12), NADP (EC 1.2.1.13) or either (EC 1.2.1.59). The family corresponds to the ubiquitous NAD+ or NADP+ utilizing type I GAPDH and a small clade of dehydrogenases, called erythrose-4-phosphate dehydrogenase (E4PDH) proteins, which utilize NAD+ to oxidize erythrose-4-phosphate (E4P) to 4-phospho-erythronate, a precursor for the de novo synthesis of pyridoxine via 4-hydroxythreonine and D-1-deoxyxylulose. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",