Kidney glucose 6-phosphatase

Sein KT, Chu N. 1979. Liver and Kidney glucose-6-phosphatase levels in carbon tetrachlolride - and PDT - administered mice. Enzyme 24 72-74. 

No gross or microscopic lesions were observed in the kidneys of rats treated dermally with 100 mg nickel/kg/day as nickel sulfate for 15 or 30 days (Mathur et al. 1977). In this study, there was no indication that the rats were prevented from licking the nickel from the skin therefore, the animals could have been orally exposed. Increased Mg ATPase was observed in the kidneys of guinea pigs treated with 100 mg nickel/kg/day as nickel sulfate placed on skin of the back for 30 days (Mathur and Gupta 1994). No effect was noted at 15 days, and dermal nickel exposure had no effect on kidney acid phosphatase or glucose-6-phosphatase activities. 

Fructose-1,6-bisphosphatase deficiency, first describ ed by Baker and Winegrad in 1970, has now been reported in approximately 30 cases. It is more common in women and is inherited as an autosomal recessive disorder. Initial manifestations are not strikingly dissimilar from those of glucose-6-phosphatase deficiency. Neonatal hypoglycemia is a common presenting feature, associated with profound metabolic acidosis, irritability or coma, apneic spells, dyspnea, tachycardia, hypotonia and moderate hepatomegaly. Lactate, alanine, uric acid and ketone bodies are elevated in the blood and urine [11]. The enzyme is deficient in liver, kidney, jejunum and leukocytes. Muscle fructose-1,6-bisphosphatase activity is normal. 

Phosphoenolpyruvate carboxykinase (PEPCK) deficiency is distinctly rare and even more devastating clinically than deficiencies of glucose-6-phosphatase or fructose-1,6-bisphosphatase. PEPCK activity is almost equally distributed between a cytosolic form and a mitochondrial form. These two forms have similar molecular weights but differ by their kinetic and immunochemical properties. The cytosolic activity is responsive to fasting and various hormonal stimuli. Hypoglycemia is severe and intractable in the absence of PEPCK [12]. A young child with cytosolic PEPCK deficiency had severe cerebral atrophy, optic atrophy and fatty infiltration of liver and kidney. 

Glucose-6-phosphatase is found only in liver and kidney, and allows these tissues to supply glucose to other organs of the body, like the brain, which have little or no reserves of carbohydrates. 

Type la (von Gierke s) Glucose 6-phosphatase Liver Enlarged liver, kidney failure... 

It appears to the author that the existence of a distinct glucose-6-phosphatase is well established for endoplasmic reticulum of liver, kidney, small intestine, and pancreas but additional studies appear to be required before a similar conclusion may be reached regarding the enzyme from other sources. It should be pointed out, however, that while glucose-6-P hydrolysis by enzymes from many sources may not result from specific glucose-6-phosphatase, this hydrolysis in these tissues may nonetheless be of metabolic significance. 

Comparison of Levels of Phosphotransferase and Phosphohydrolase Activities of Glucose-6-Phosphatase in Liver, Kidney, and Small Intestine of Rabbit"... 

Reported Presence of Glucose-6-phosphatase in Vertebrate Kidney... 

Another indication of the difference between the metabolic roles of muscle, a consumer tissue and liver, a contributer tissue, is the enzyme glucose-6-phospha-tase. This enzyme is required for the production of neutral glucose. It is present in liver and kidney but not in strict consumer tissues, such as muscle and brain. Without glu-cose-6-phosphatase the glucose-6-phosphate cannot be converted to dephosphorylated glucose, which is necessary for... 

The main site of gluconeogenesis is the liver, although it also occurs to a far lesser extent in the kidneys. Very little gluconeogenesis occurs in brain or muscle. Within liver cells, the first enzyme of gluconeogenesis, pyruvate carboxylase, is located in the mitochondrial matrix. The last enzyme, glucose 6-phosphatase is bound to the smooth endoplasmic reticulum. The other enzymes of the pathway are located in the cytosol. 

For the glucose producing cells in the liver and kidneys, there is a balance between the glucokinase and glucose-6-phosphatase GP, which can be called a push-push system. The net hepatic glucose output, Jhgo. can be described by ... 

Finally, as previously mentioned, it can be dephosphorylated to free glucose. This is the final step in gluconeogenesis that takes place in liver and kidneys. Other tissues have no or only little glucose-6-phosphatase, so they cannot form free glucose from G6P. 

I (lA and IB) Glucose-6-phosphatase von Gierke s disease Enlarged liver and kidney slowed growth very low blood sugar levels abnormally high levels of acid, fats and uric acid in blood growth failure... 

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