Phosphoramidates. V. Probable identity of rat liver microsomal glucose 6-phosphatase, phosphoramidase, and phosphoramidate-hexose phosphotransferase

Parvin, Rokshana; Smith, Rhona

doi:10.1021/bi00832a058

Cited by 38 publications

(8 citation statements)

References 24 publications

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“…1 mM) [20] that produced no appreciable effect on any of the Nphosphatases described herein. That enzyme also is associated with microsomes [21], while the present phosphopolyhistidine and phosphopolylysine phosphatase activities were soluble. The phosphatases that act on the free phosphoamino acids phosphoarginine, 3-phosphohistidine and phospholysine all bind strongly to CM-type, but not to DEAE-type, ion-exchange resins [22,23].…”

Section: Discussionmentioning

confidence: 81%

Phosphohistidine and phospholysine phosphatase activities in the rat: potential protein-lysine and protein-histidine phosphatases?

Wong

Faiola

et al. 1993

Biochemical Journal

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We have detected phosphohistidine and phospholysine phosphatase activities in rat tissue extracts using partially phosphorylated, high-molecular-mass (> 10 kDa) polymers of histidine and lysine as substrates. Multiple phosphohistidine- and phospholysine-specific phosphatases were present in these extracts based on observed differences in heat stability, sensitivity to bivalent metal ions and thiol modifying reagents, and/or elution from DE-52 cellulose. The properties of these phosphohistidine and phospholysine phosphatases were distinct from those of the phosphomonoester-specific protein phosphatases or the N-P phosphohydrolases that act on the free phosphoamino acids phosphoarginine, 3-phosphohistidine or phospholysine.

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Section: Discussionmentioning

confidence: 81%

Phosphohistidine and phospholysine phosphatase activities in the rat: potential protein-lysine and protein-histidine phosphatases?

Wong

Faiola

et al. 1993

Biochemical Journal

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“…The key active site residues in Glc-6-Pase-␣ have been characterized (21,22) and shown to lie facing into the lumen of the ER. During catalysis, Glc-6-Pase-␣ forms a phosphoryl enzyme intermediate (23)(24)(25)(26) by the formation of a covalent bond between the phosphoryl group of Glc-6-P and His 176 in Glc-6-Pase-␣ (21).…”

Section: Discussionmentioning

confidence: 99%

Histidine 167 Is the Phosphate Acceptor in Glucose-6-phosphatase-β Forming a Phosphohistidine Enzyme Intermediate during Catalysis

Ghosh¹,

Shieh²,

Pan

et al. 2004

Journal of Biological Chemistry

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The glucose-6-phosphatase (Glc-6-Pase) family comprises two active endoplasmic reticulum (ER)-associated isozymes: the liver/kidney/intestine Glc-6-Pase-␣ and the ubiquitous Glc-6-Pase-␤. Both share similar kinetic properties. Sequence alignments predict the two proteins are structurally similar. During glucose 6-phosphate (Glc-6-P) hydrolysis, Glc-6-Pase-␣, a nine-transmembrane domain protein, forms a covalently bound phosphoryl enzyme intermediate through His 176 , which lies on the lumenal side of the ER membrane. We showed that Glc-6-Pase-␤ is also a nine-transmembrane domain protein that forms a covalently bound phosphoryl enzyme intermediate during Glc-6-P hydrolysis. However, the intermediate was not detectable in Glc-6-Pase-␤ active site mutants R79A, H114A, and H167A. Using [ 32 P]Glc-6-P coupled with cyanogen bromide mapping, we demonstrated that the phosphate acceptor in Glc-6-Pase-␤ is His 167 and that it lies inside the ER lumen with the active site residues, Arg 79 and His 114 . Therefore Glc-6-Pase-␣ and Glc-6-Pase-␤ share a similar active site structure, topology, and mechanism of action.The glucose-6-phosphatase (Glc-6-Pase) 1 family is composed of three proteins: Glc-6-Pase-␣ (1-4), Glc-6-Pase-␤ (5-7) (previously known as UGRP (ubiquitously expressed Glc-6-Pase related protein)), and islet-specific Glc-6-Pase-related protein (8,9). Whereas Glc-6-Pase-␣ and Glc-6-Pase-␤ are functional phosphohydrolases, the islet-specific Glc-6-Pase-related protein lacks enzymatic activity.The prototype of the family, Glc-6-Pase-␣, is a 357-amino acid, nine-transmembrane domain, endoplasmic reticulum (ER)-associated protein (10, 11), which is expressed primarily in the liver, kidney, and intestine (12, 13). Glc-6-Pase-␣ catalyzes the hydrolysis of glucose 6-phosphate (Glc-6-P) to glucose in the terminal step of gluconeogenesis and glycogenolysis (13). Between meals, the resulting release of glucose to the blood maintains glucose homeostasis. Naturally occurring loss of function mutations in Glc-6-Pase-␣ cause glycogen storage disease type Ia, a disorder that is characterized by loss of blood glucose homeostasis and disorders of glycogen and lipid metabolism (reviewed in Refs. 14 and 15).Glc-6-Pase-␤ is a ubiquitously expressed, 346-amino acid membrane protein that shares a 36% sequence identity to Glc-6-Pase-␣ (5-7). Despite the absence of any apparent ER retention motif, Glc-6-Pase-␤ is also localized in the ER membrane (6), although its orientation in the membrane is not known. The subcellular localization of the Glc-6-Pase-␤ active site is not known, although it is assumed to be similar to Glc-6-Pase-␣. Both Glc-6-Pase-␤ and Glc-6-Pase-␣ couple with the Glc-6-P transporter to form an active Glc-6-Pase complex, and both share similar kinetic properties with respect to Glc-6-P hydrolysis (6).The active site of Glc-6-Pase-␣ was originally identified by the presence of a conserved phosphatase signature motif found in lipid phosphatases, acid phosphatases, and vanadium haloperoxidases (16,17). This motif was show...

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“…Both systems display evidence for a phosphoryl-enzyme intermediate and the latter is inhibited by citrate, as is glucose 6-phosphatase (134,170,176). The formation of a 32P-labeled phosphoryl enzyme complex formed by action of E. coli alkaline phosphatase on G632P was reported several years ago (177,178), and there is now evidence for phosphorylation of rat-liver microsomes from G632P, the label being incorporated as N-3-phosphoryl histidine (179,180).…”

Section: B Distribution and Multiple Activities Of Glucose 6-phosphamentioning

confidence: 91%

New Aspects of Glycogen Metabolism

Ryman¹,

Whelan²

1971

Advances in Enzymology - And Related Areas of Molecular Biology

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Phosphoramidates. V. Probable identity of rat liver microsomal glucose 6-phosphatase, phosphoramidase, and phosphoramidate-hexose phosphotransferase

Cited by 38 publications

References 24 publications

Phosphohistidine and phospholysine phosphatase activities in the rat: potential protein-lysine and protein-histidine phosphatases?

Phosphohistidine and phospholysine phosphatase activities in the rat: potential protein-lysine and protein-histidine phosphatases?

Histidine 167 Is the Phosphate Acceptor in Glucose-6-phosphatase-β Forming a Phosphohistidine Enzyme Intermediate during Catalysis

New Aspects of Glycogen Metabolism

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