Multiple molecular forms of ATP: Hexose 6-phosphotransferase from rat liver

González, Carmen; Ureta, Tito; Sanchez, Ramon; Niemeyer, Hermann M.

doi:10.1016/0006-291x(64)90038-5

Cited by 157 publications

(42 citation statements)

References 9 publications

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“…Four distinct isozymes of hexokinase were separated by ion exchange chromatography (González et al, 1964) or electrophoresis (Katzen and Schimke, 1965) of extracts from various mammalian tissues. Generally these are referred to as the Type I, Type II, Type III and Type IV isozymes, with the latter commonly called 'glucokinase'.…”

Section: Isozymes Of Mammalian Hexokinasementioning

confidence: 99%

Isozymes of mammalian hexokinase: structure, subcellular localization and metabolic function

Wilson

2003

Journal of Experimental Biology

942

905

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SUMMARY The first step in metabolism of glucose (Glc) is usually phosphorylation,catalyzed by hexokinase. However, the Glc-6-P produced can then enter one or more of several alternative pathways. Selective expression of isozymic forms of hexokinase, differing in catalytic and regulatory properties as well as subcellular localization, is likely to be an important factor in determining the pattern of Glc metabolism in mammalian tissues/cells. Despite their overall structural similarity, the Type I, Type II and Type III isozymes differ in important respects. All three isozymes are inhibited by the product,Glc-6-P, but with the Type I isozyme, this inhibition is antagonized by PI, whereas with the Type II and Type III isozymes, Piactually causes additional inhibition. Reciprocal changes in intracellular levels of Glc-6-P and Pi are closely associated with cellular energy status, and it is proposed that the response of the Type I isozyme to these effectors adapts it for catabolic function, introducing Glc into glycolytic metabolism for energy production. In contrast, the Type II, and probably the Type III, isozymes are suggested to serve primarily anabolic functions, e.g. to provide Glc-6-P for glycogen synthesis or metabolism via the pentose phosphate pathway for lipid synthesis. Type I hexokinase binds to mitochondria through interaction with porin, the protein that forms channels through which metabolites traverse the outer mitochondrial membrane. Several experimental approaches have led to the conclusion that the Type I isozyme, bound to actively phosphorylating mitochondria, selectively uses intramitochondrial ATP as substrate. Such interactions are thought to facilitate coordination of the introduction of Glc into glycolysis, via the hexokinase reaction, with the terminal oxidative stages of Glc metabolism occurring in the mitochondria, thus ensuring an overall rate of Glc metabolism commensurate with cellular energy demands and avoiding excessive production of lactate. The Type II isozyme also binds to mitochondria. Whether such coupling occurs with mitochondrially bound Type II hexokinase in normal tissues, and how it might be related to the proposed anabolic role of this isozyme, remain to be determined. The Type III isozyme lacks the hydrophobic N-terminal sequence known to be critical for binding of the Type I and Type II isozymes to mitochondria. Immunolocalization studies have indicated that, in many cell types, the Type III has a perinuclear localization, the possible metabolic consequences of which remain unclear.

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Section: Isozymes Of Mammalian Hexokinasementioning

confidence: 99%

Isozymes of mammalian hexokinase: structure, subcellular localization and metabolic function

Wilson

2003

Journal of Experimental Biology

942

905

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“…It has been recognized for a number of years that the livers of rats and other species contain several enzymes capable of catalysing the phosphorylation of glucose by ATP (Gonzalez et al, 1964). These have been resolved by electrophoresis (Katzen et al, 1965) into three 'low Kmn' hexokinases (EC 2.7.1.1) and one 'high-Km' glucokinase (EC 2.7.1.2).…”

mentioning

confidence: 99%

Glycolytic and gluconeogenic enzyme activities in parenchymal and non-parenchymal cells from mouse liver

Crisp

Pogson

1972

Biochemical Journal

130

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Parenchymal cells contain both glucose 6-phosphatase and fructose 1,6-diphosphatase. The non-parenchymal fraction appears to contain fructose 1,6-diphosphatase, but is devoid of glucose 6-phosphatase. 8. No aldolase A was detectable in the whole liver. Aldolase B occurs in both parenchymal and non-parenchymal tissue. 9. Parenchymal cells prepared by mechanical disruption ofmouse liver with 20 % polyvinyl alcohol exhibit a similar enzyme profile to those prepared enzymically. 10. The methodology involved in the preparation of isolated liver cells is discussed. The importance of the measurement of several parameters as criteria for establishing the viability of parenchymal cells is stressed. 11. The metabolic implications of the results in the present study are discussed.

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“…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). Hexokinase IV (or D) is most often called glucokinase (GCK), although it is not specific for glucose (Cárdenas et al, 1998;Wilson, 2004).…”

Section: Glucokinase and The Vertebrate Hexokinase Gene Familymentioning

confidence: 99%

Evolution of glucose utilization: Glucokinase and glucokinase regulator protein

Irwin

2014

Molecular Phylogenetics and Evolution

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Glucose is an essential nutrient that must be distributed throughout the body to provide energy to sustain physiological functions. Glucose is delivered to distant tissues via be blood stream, and complex systems have evolved to maintain the levels of glucose within a narrow physiological range. Phosphorylation of glucose, by glucokinase, is an essential component of glucose homeostasis, both from the regulatory and metabolic point-of-view. Here we review the evolution of glucose utilization from the perspective of glucokinase. We discuss the origin of glucokinase, its evolution within the hexokinase gene family, and the evolution of its interacting regulatory partner, glucokinase regulatory protein (GCKR). Evolution of the structure and sequence of both glucokinase and GCKR have been necessary to optimize glucokinase in its role in glucose metabolism.

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Multiple molecular forms of ATP: Hexose 6-phosphotransferase from rat liver

Cited by 157 publications

References 9 publications

Isozymes of mammalian hexokinase: structure, subcellular localization and metabolic function

Isozymes of mammalian hexokinase: structure, subcellular localization and metabolic function

Glycolytic and gluconeogenic enzyme activities in parenchymal and non-parenchymal cells from mouse liver

Evolution of glucose utilization: Glucokinase and glucokinase regulator protein

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