Nucleotide-Binding Domain of the sugar kinase/HSP70/actin superfamily
This superfamily includes the actin family, the HSP70 family of molecular chaperones and nucleotide exchange factors, the ROK (repressor, ORF, kinase) family, the hexokinase family, the FGGY family (which includes glycerol kinase and similar carbohydrate kinases such as rhamnulokinase and xylulokinase), the exopolyphosphatase/guanosine pentaphosphate phosphohydrolase/nucleoside triphosphate diphosphohydrolase family, propionate kinase/acetate kinase family, glycerol dehydratase reactivase, 2-hydroxyglutaryl-CoA dehydratase component A, N-acetylglucosamine kinase, butyrate kinase 2, Escherichia coli YeaZ and similar glycoproteases, the cell shape-determining protein MreB, the plasmid DNA segregation factor ParM, cell cycle proteins FtsA, Pili assembly protein PilM, ethanolamine utilization protein EutJ, and similar proteins. The nucleotide-binding site residues are conserved; the nucleotide sits in a deep cleft formed between the two lobes of the nucleotide-binding domain (NBD). Substrate binding to superfamily members is associated with closure of this catalytic site cleft. The functional activities of several members of the superfamily, including hexokinases, actin, and HSP70s, are modulated by allosteric effectors, which may act on the cleft closure.