Glucose‐6‐Phosphatase: Two Concepts of Membrane‐Function Relationship

Sukalski, Katherine A.; Nordlie, Robert C.

doi:10.1002/9780470123089.ch3

Cited by 17 publications

(6 citation statements)

References 42 publications

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“…This enzyme plays an important role in regulation of glucose homeostasis [27], both as a glucogeneogenic and glycogenolitical enzyme, catalyzing the critical step of the glucose synthesis [28]. Our results are consistent with previous research from Mithieux [29], who suggest that intensified glycogenolysis contributes to increased activity of glucose-6-phosphatase.…”

Section: Discussionsupporting

confidence: 92%

Liver Carbohydrate Metabolism in Rats in the Period of Recovery after Acute Heat Stress

et al. 2013

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In the present work we have estimated the effect of acute heat stress (1 hour to 41±0,5°C) and the different period of recovery at room temperature after the heat stress (0, 30 minutes, 1, 6, 12, 24, 48 and 96 hours) over the hepatic carbohydrate-related enzymes and substrates of rats.The obtained results can be summarized in three phases: up to 6 th hour, from 6 th to 24 th hour and form 24 th up to 96 th hour of recovery after the heat stress. Acute heat stress (up to 1hour of recovery) caused intensive glycogenolysis, associated with moderate, but non-significant endogenous production of glucose. The period of 6 th to 24 th hour of recovery after exposure to acute heat stress, is characterized with intensive rebound of glycogen stores, with decreased glucose production, and finally, from the 48 th up to 96 th hour of recovery, process of glycogenolysis is still evident, even though less intensive than the first hours after the heat stress.Overall, we can conclude that acute heat stress and the period of recovery after the heat stress are followed with dynamic changes of the liver carbohydrate-relates enzymes and substrates in a course of elevated glycogenolysis, but decreased glycolysis and gluconeogenesis.

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Section: Discussionsupporting

confidence: 92%

Liver Carbohydrate Metabolism in Rats in the Period of Recovery after Acute Heat Stress

et al. 2013

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“…We have previously reviewed, frequently and in detail, characteristics of this enzyme system, and I refer the interested reader to a selected few (Nordlie 1971, 1974, 1976b; Nordlie and Sukalski 1982; Sukalski and Nordlie 1989; Nordlie et al 1993b; Foster et al 1997; Nordlie et al 1999; Foster and Nordlie 2002). I will therefore zero in on two aspects, dealing with kinetics (ala Fromm) and control (ala Lardy), which truly reflect the major focus of my professional life.…”

Section: Some Characteristics Of the Glucose-6-phosphatase Systemmentioning

confidence: 99%

“…Two models have been proposed (Sukalski and Nordlie 1989) to explain the differential, discriminant latency — the substrate translocase-catalytic unit model first proposed by Arion (Arion et al 1975), and the combined conformational flexibility substrate transport model of Alfred Berteloot and Gerald van de Werve (Berteloot et al 1995). The former model (Fig.…”

Section: Some Characteristics Of the Glucose-6-phosphatase Systemmentioning

confidence: 99%

“…3) includes the multiplicity of activities inherent in the glucose-6-phosphatase system, and has support from molecular genetics studies (Waddell et al 1988; Pan et al 1999). The interested reader is referred also to the intriguing combined conformational flexibility-substrate transport model which is described in detail elsewhere (Sukalski and Nordlie 1989; Berteloot et al 1995). …”

Section: Some Characteristics Of the Glucose-6-phosphatase Systemmentioning

confidence: 99%

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A retrospective review of the roles of multifunctional glucose-6-phosphatase in blood glucose homeostasis: Genesis of the tuning/retuning hypothesis

Nordlie

Foster

2010

Life Sciences

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In a scientific career spanning from 1955-2000, my research focused on phosphoenolpyruvate carboxykinase and glucose-6-phosphatase. Grounded in basic enzymology, and initially pursuing the steady-state rate behavior of isolated preparations of these critically important gluconeogenic enzymes, our key findings were confirmed and extended by in situ enzyme rate experiments exploiting isolated liver perfusions. These efforts culminated in the discovery of the liver cytosolic isozyme of carboxykinase, known today as (GTP)PEPCK-C (EC4.1.1.32) and also revealed a biosynthetic function and multicomponent nature of glucose-6-phosphatase (EC3.1.3.9). Discovery that glucose-6-phosphatase possessed an intrinsically biosynthetic activity, now known as carbamyl-P:glucose phosphotransferase-along with a deeper consideration of the enzyme's hydrolytic activity as well as the action of liver glucokinase resulted in the evolution of Tuning/ Retuning Hypothesis for blood glucose homeostasis in health and disease. This THEN & NOW review shares with the reader the joy and exhilaration of major scientific discovery and also contrasts the methodologies and approaches on which I relied with those currently in use.

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“…Although glycogen stored in muscle and liver are structurally identical, these two glycogen pools play different physiological roles during a fasting period. Muscle glycogen is used endogenously because muscle lacks the glucose-6-phosphatase (G6Pase), while liver possess G6Pase activity, allowing this organ to convert glucose-6-phosphate to glucose and released into blood circulation (Sukalski and Nordlie, 1989). Therefore, liver glycogen has an important role in maintaining systemic glucose homeostasis.…”

Section: Glycogen Metabolismmentioning

confidence: 99%