Evolution and regulatory role of the hexokinases

Evolution of glucose utilization: Glucokinase and glucokinase regulator protein

“…Enzymes, called hexokinases, phosphorylate glucose, and other six-carbon sugars. In mammals, and other vertebrates, four hexokinase isozymes have been identified (Ureta, 1982;Wilson, 1995Wilson, , 1997Wilson, , 2003Wilson, , 2004Cárdenas et al, 1998). The different isozymes of hexokinase were initially distinguished by letters (i.e., hexokinase (HK) A, B, C, and D) based on their elution time from DEAE cellulose columns (González et al, 1964), but subsequently given numbers (i.e., hexokinase I, II, III, and IV) based on their migration in electrophoretic gels (Katzen et al, 1965).…”

“…The different isozymes of hexokinase were initially distinguished by letters (i.e., hexokinase (HK) A, B, C, and D) based on their elution time from DEAE cellulose columns (González et al, 1964), but subsequently given numbers (i.e., hexokinase I, II, III, and IV) based on their migration in electrophoretic gels (Katzen et al, 1965). Hexokinase IV (or D) is most often called glucokinase (GCK), although it is not specific for glucose (Cárdenas et al, 1998;Wilson, 2004). Genes encoding these hexokinases use Arabic numbers; e.g., HK1 encodes hexokinase I. Mammalian hexokinases have been extensively characterized, with possibly their most striking difference being their molecular weights (Ureta, 1982;Wilson, 1995Wilson, , 1997Wilson, , 2003Wilson, , 2004Cárdenas et al, 1998).…”

“…Hexokinase IV (or D) is most often called glucokinase (GCK), although it is not specific for glucose (Cárdenas et al, 1998;Wilson, 2004). Genes encoding these hexokinases use Arabic numbers; e.g., HK1 encodes hexokinase I. Mammalian hexokinases have been extensively characterized, with possibly their most striking difference being their molecular weights (Ureta, 1982;Wilson, 1995Wilson, , 1997Wilson, , 2003Wilson, , 2004Cárdenas et al, 1998). Hexokinases I, II, and III have a molecular weight of approximately 100kD, while glucokinase has a molecular mass of about 50kD.…”

“…Hexokinases I, II, and III have a molecular weight of approximately 100kD, while glucokinase has a molecular mass of about 50kD. Hexokinases having a molecular weight of 50kD, but not 100kD, have also been found, and characterized, in many other eukaryotes species, including nonvertebrate animals, plants, and yeast (Ureta, 1982;Wilson, 1995Wilson, , 1997Wilson, , 2003Wilson, , 2004Cárdenas et al, 1998). In some of these non-mammalian species multiple isozymes have been characterized (Wilson, 1995(Wilson, , 2004Cárdenas et al, 1998).…”

“…While enzymes that phosphorylate sugars have also found in bacteria, these sequences show no significant sequence similarity to the eukaryotic hexokinases. However there is some similarity in the three-dimensional structures of hexokinases from bacteria and eukaryotes, which has been used to suggest that they share a common ancestor (Bork et al, 1993;Cárdenas et al, 1998;Kawai et al, 2005).…”