Comparison of the primary sequences of two potato tuber ADP-glucose pyrophosphorylase subunits

Nakata, Paul A.; Greene, Thomas W.; Anderson, Joseph M.; Smith-White, Brian; Okita, Thomas W.; Preiss, Jack

doi:10.1007/bf00037149

Cited by 85 publications

(64 citation statements)

References 21 publications

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“…The endosperm enzyme is composed of two subunit types of 51 and 60 kD (nonproteolyzed), which compares favorably with the values of about 50 to 56 kD (small subunit) and 51 to 60 kD (large subunit) reported for AGPs from other tissues (Sowokinos and Preiss, 1982;More11 et al, 1987;Plaxton and Preiss, 1987;Anderson et al, 1989;Preiss et al, 1989;Okita et al, 1990;Nakata et al, 1991;Nakamura and Kawaguchi, 1992;Smith-White and Preiss, 1992). The enzyme has high pyrophosphorolytic activity in crude extracts when assayed without 3-PGA and Pi (Table I); this activity is comparable to or higher than that previously reported for the 3-PGA-activated crude AGP from potato tubers (Sowokinos and Preiss, 1982;Okita et al, 1990), maize seeds (Plaxton and Preiss, 1987), or leaves of severa1 species (Sanwal et al, 1968).…”

Section: Discussionsupporting

confidence: 56%

“…The design and sequence of the synthetic peptide that was used for production of antibodies specific for the large subunit of barley endosperm AGP. Aligned are the corresponding sequences for the large subunit (is) of AGP from barley endosperm (P. Villand, unpublished results) and potato tubers (Nakata et al, 1991), and for the small subunit (Ss) of AGP from barley endosperm (P. Villand, unpublished results) and potato tubers (Miiller-Rober et al, 1990). Amino acids identical to those present in the synthetic peptide are shaded.…”

Section: Other Methodsmentioning

confidence: 99%

“…For the pyrophosphorolytic reaction, a range of 3-PGA concentrations from 0.01 to 10 mM had either no effect (up to 0.2 mM) or inhibited the crude enzyme, both in the presence or absence of Pi (see Table I, and data not shown). Pi, a well-known inhibitor of AGP (Sanwal et al, 1968;Preiss, 1991), was relatively ineffective in inhibiting both barley AGP reactions. Under assay conditions of near-saturating concentrations of ATP or ADPglucose, 20 HIM Pi caused only about 15 and 30% inhibition of the forward and reverse reactions, respectively (Table I).…”

Section: Activity In Crude Extractsmentioning

confidence: 96%

“…Extracts of barley endosperm were found to contain high pyrophosphorolytic activity of AGP (Table I) when assayed in the absence of 3-PGA, an essential activator of higher plant AGP (Sanwal et al, 1968;Preiss, 1991). Rates of up to 0.5 ^mol of glucose-1-P formed min" 1 mg~' of protein (25°C) have been determined for several preparations of crude barley endosperm AGP.…”

Section: Activity In Crude Extractsmentioning

confidence: 99%

“…The higher plant enzyme, which is composed of two different subunit types (More11 et al, 1987;Okita et al, 1990), is characterized by a potent activation by 3-PGA and inhibition by Pi (Sanwal et al, 1968;Preiss, 1991). The activation (3-PGA) and inhibition (Pi) constants for AGP are usually on the order of micromolar (Sanwal et al, 1968;Sowokinos, 1981;Sowokinos and Preiss, 1982;Plaxton and Preiss, 1987), and the ratio of the two effectors is believed to play a key * Corresponding author; fax 47-9-941465. role in the control of starch biosynthesis (Neuhaus and Stitt, 1990;Preiss, 1991). The fine regulation by 3-PGA and Pi has been demonstrated for AGP from both photosynthetic and nonphotosynthetic plant tissues (Sanwal et al, 1968;Sowokinos, 1981;Sowokinos and Preiss, 1982;Plaxton and Preiss, 1987;Preiss, 1991).…”

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confidence: 99%

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Insensitivity of Barley Endosperm ADP-Glucose Pyrophosphorylase to 3-Phosphoglycerate and Orthophosphate Regulation

et al. 1993

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Crude extracts of starchy endosperm from barley (Hordeum vdgare cv Bomi) contained high pyrophosphorolytic activity (up to 0.5 pmol of glucose-1-P formed min-' mg-' of protein) of ADPglucose pyrophosphorylase (ACP) when assayed in the absence of 3-phosphoglycerate (3-PCA). This high activity was observed regardless of whether ACP had been extracted in the presence or absence of various protease inhibitors or other protectants. Western blot analysis using antibodies specific for either the small or large subunit of the enzyme demonstrated that the large, 60-kD subunit was prone to proteolysis in crude extracts, with a half-time of degradation at 4°C (from 60 to 53 to 51 kD) on the order of minutes. The presence of high concentrations of protease inhibitors decreased, but did not prevent this proteolysis. The small, 51-kD subunit of barley endosperm ACP was relatively resistant to proteolysis, both in the presence or absence of protease inhibitors. For the crude, nonproteolyzed enzyme, 3-PCA acted as a weak activator of the ADP-glucose synthetic reaction (about 25% activation), whereas in the reverse reaction (pyrophosphorolysis) it served as an inhibitor rather than an activator. For both the synthetic and pyrophosphorolytic reactions, inorganic phosphate (Pi) acted as a weak competitive or mixed inhibitor of ACP. The relative insensitivity to 3-PCA/Pi regulation has been observed with both the nonproteolyzed crude enzyme and partially purified (over 60-fold) ACP, the latter characterized by two bands for the large subunit (molecular masses of 53 and 51 kD) and one band for the small subunit (51 kD). Addition of 3-PCA to assays of the partially purified, proteolyzed enzyme had little or no effect on the K,,, values of all substrates of ACP, but it reduced the Hill coefficient for ATP (from 2.1 to 1.0). These findings are discussed with respect to previous reports on the structure and regulation of higher plant ACP.

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Section: Discussionsupporting

confidence: 56%

Section: Other Methodsmentioning

confidence: 99%

Section: Activity In Crude Extractsmentioning

confidence: 96%

Section: Activity In Crude Extractsmentioning

confidence: 99%

mentioning

confidence: 99%

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Insensitivity of Barley Endosperm ADP-Glucose Pyrophosphorylase to 3-Phosphoglycerate and Orthophosphate Regulation

et al. 1993

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Starch Biosynthesis in Plants

Preiss

2008

Wiley Encyclopedia of Chemical Biology

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Starch is a major storage compound in plants that is present both in leaves and in storage tissues. Biochemical and molecular biological data show that ADP‐glucose is the glucosyl donor for plant starch synthesis, and its synthesis is catalyzed by ADP‐glucose pyrophosphorylase. Subsequently, starch synthases catalyze the transfer of the glucosyl residue from ADP‐glucose to the oligosaccharide chains of the starch components amylose and amylopectin to form new α‐1,4‐glucosidic residues. After elongation of these α‐1,4‐glucosidic chains, the branching enzyme catalyzes a cleavage of the elongated chain and transfers the cleaved portion of the oligosaccharide chain to either another region in the amylopectin molecule or to a new amylopectin and forms a new α‐1,6‐glucosidic linkage. Amylose synthesis is catalyzed by the granule‐bound starch synthase. Regulation of starch synthesis occurs at the ADP‐glucose pyrophosphorylase step. The enzyme from higher plants, green algae, and cyanobacteria is activated allosterically by 3‐phosphoglycerate and inhibited by inorganic phosphate. Isolation of mutants and control analyses indicate that the allosteric activation and inhibition are of physiological and functional importance in the regulation of starch synthesis. Furthermore, evidence indicates that ADP‐glucose pyrophosphorylases can also be regulated by a redox mechanism. The current knowledge of the enzyme structures and critical amino acids necessary for substrate binding, allosteric effector binding, regulation, and catalysis for the ADP‐glucose pyrophosphorylase is reviewed.

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