Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.1.2.13 (aldolase)
3,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The presence of glycolytic enzymes and a GLUT-1-type glucose transporter in rod and cone outer segments was determined by enzyme activity assays, glucose uptake measurements, Western blotting, and immunofluorescence microscopy. Enzyme activities of six glycolytic enzymes including hexokinase, phosphofructokinase, aldolase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, pyruvate kinase, and lactate dehydrogenase, were found to be present in purified rod outer segment (ROS) preparations. Immunofluorescence microscopy of bovine and chicken retina sections labeled with monoclonal antibodies against glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, and lactate dehydrogenase have confirmed that these enzymes are present in rod and cone outer segments and not simply contaminants from the inner segments or other cells. Rod outer segments were also found to contain glucose transport activity as detected by 3-O-[14C]methylglucose uptake and exchange. The glucose transporter had a Km of 6.3 mM and a Vmax of 0.15 nmol of 3-O-methylglucose/s/mg of ROS membrane protein for net uptake and a Km of 29 mM and a Vmax of 1.06 nmol of 3-O-methylglucose/s/mg of ROS membrane protein for equilibrium exchange. These Km values for net uptake and equilibrium exchange are similar to values obtained for human red blood cells and are characteristic of GLUT-1-type glucose transporter. The transport was inhibited by both cytochalasin B and phloretin. Western blot analysis and immunofluorescence microscopy using type-specific glucose transporter antibodies indicated that both rod and cone outer segment plasma membranes have a GLUT-1 glucose transporter of Mr 45K as found in red blood cells and brain microsomal membranes. Solid-phase radioimmune competitive inhibition studies indicated that rod outer segment plasma membranes contained 15% the number of glucose transporters found in human red blood cell membranes and had an estimated density of 400 glucose transporter per micron2 of plasma membrane. These studies support the view that outer segments can generate energy in the form of ATP and GTP by anaerobic glycolysis to supply at least some of the energy requirements for phototransduction and other metabolic processes.
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PMID:Glycolytic enzymes and a GLUT-1 glucose transporter in the outer segments of rod and cone photoreceptor cells. 193 98

Subpellicular microtubules isolated from Trypanosoma brucei parasites were fractionated on a phosphocellulose column, and the trypanosomal p52 microtubule-associated protein was eluted along with two other proteins of 41 and 36 kDa. These proteins were found to be the glycosomal enzymes aldolase (41 kDa) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH, 36 kDa) by enzyme activity, antibody cross-reaction, and N-terminal sequencing. These enzymes were coprecipitated with tubulin in the presence of taxol, and aldolase had the capacity to polymerize tubulin and crosslink microtubules. Immunolocalization of anti-aldolase and anti-GAPDH antibodies did not show an interaction between these enzymes and the subpellicular microtubules. The question whether the copurification of aldolase and the subpellicular microtubules could reflect a physiological phenomenon or may be an experimental artifact is discussed.
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PMID:The association of glycosomal enzymes and microtubules: a physiological phenomenon or an experimental artifact? 197 42

Time-resolved phosphorescence anisotropy has been used to study the rotational diffusion of eosin-labeled human erythrocyte band 3 in the presence of an enzyme bound at its cytoplasmic pole. With increasing amounts of G3PD (glyceraldehyde-3-phosphate dehydrogenase) added to ghosts, the infinite time anisotropy (r infinity) increases, and at saturating concentrations, very little decay of the anisotropy r(t) occurs at all. These phenomena are reversed by elution of the enzyme with 150 mM NaCl. Prior proteolytic removal of the N-terminal 41-kDa cytoplasmic fragment of band 3 also disenables the G3PD effect. When ghosts are stripped of their residually bound G3PD, a small reduction in the fraction of immobile band 3 is observed. Finally, titration of band 3 sites with aldolase shows effects on the r(t) qualitatively similar to those observed with G3PD. On the basis of our interpretation of the heterogenous anisotropy decay of eosin-labeled band 3 [Matayoshi, E. D., & Jovin, T. M. (1991) Biochemistry (preceding paper in this issue)], we conclude that the binding of G3PD and aldolase results in the immobilization of band 3 oligomers.
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PMID:Rotational diffusion of band 3 in erythrocyte membranes. 2. Binding of cytoplasmic enzymes. 201 12

The cellular distribution of free and bound glycolytic enzymes in vivo was estimated by means of a model based on previously determined association constants for individual binding interactions and in vivo protein concentrations. The calculations revealed that a significant proportion of the enzymes would be either associated with F-actin, or bound in binary enzyme-enzyme complexes in vivo. An analysis of the relative concentration, and relative activity, of F-actin-bound enzymes suggested that a complete glycolytic complex, composed of all enzymatic steps from phosphofructokinase (PFK) to lactate dehydrogenase (LDH) does not exist. This was indicated by a very low concentration of F-actin-associated phosphoglycerate kinase (PGK) and by a very low activity of F-actin bound aldolase and PGK; this model showed that aldolase and PGK would be absent from any F-actin bound complex. An analysis of soluble enzyme-enzyme associations indicated that formation of binary enzyme complexes may lead to an increased overall flux through glyceraldehyde 3-phosphate dehydrogenase and LDH, but would serve to decrease flux through PFK and aldolase. A 1.4-fold activation of PFK, which occurs when the soluble enzyme binds to F-actin, suggested that reversible binding of PFK to F-actin may represent a novel cellular mechanism for controlling glycolytic flux during periods of increased metabolic demand by controlling the key regulatory enzyme of glycolysis.
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PMID:A quantitative evaluation of the effect of enzyme complexes on the glycolytic rate in vivo: mathematical modeling of the glycolytic complex. 206 1

Accumulation of protein constituents in developing chicken breast muscle was examined by two-dimensional gel electrophoresis. Quantitative analysis of the two-dimensional gels showed a moderate coordination in accumulation among contractile proteins (actin, tropomyosin and myosin light chains) during postnatal development in spite of their isoform transition. Creatine kinase was also accumulated coordinately with contractile proteins during development. In contrast, accumulation kinetics of glycolytic enzymes (glyceraldehyde-3-phosphate dehydrogenase, aldolase and enolase) showed discoordination with those of contractile proteins. These findings suggest that there are two distinct phases in muscle maturation: (1) structural maturation and (2) metabolic maturation.
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PMID:Coordinate and discoordinate accumulation of protein constituents in chicken breast muscle. 209 Mar 33

The combination of binding and kinetic approaches is suggested to study (i) the mechanism of substrate-modulated dynamic enzyme associations; (ii) the specificity of enzyme interactions. The effect of complex formation between aldolase and glyceraldehyde-3-phosphate dehydrogenase (D-glyceraldehyde-3-phosphate:NAD+ oxidoreductase (phosphorylating), EC 1.2.1.12) on aldolase catalysis was investigated under pseudo-first-order conditions. No change in kcat but a significant increase in KM of fructose 1,6-bisphosphate for aldolase was found when both enzymes were obtained from muscle. In contrast, kcat rather than KM changed if dehydrogenase was isolated from yeast. Next, the conversion of fructose 1-phosphate was not affected by interactions between enzyme couples isolated from muscle. The influence of fructose phosphates on the enzyme-complex formation was studied by means of covalently attached fluorescent probe. We found that the interaction ws not perturbed by the presence of fructose 1-phosphate; however, fructose 1,6-bisphosphate altered the dissociation constant of the enzyme complex. A molecular model for fructose 1,6-bisphosphate-modulated enzyme interaction has been evaluated which suggests that high levels of fructose bisphosphate would drive the formation of the 'channelling' complex between aldolase and glyceraldehyde-3-phosphate dehydrogenase.
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PMID:Cooperative effect of fructose bisphosphate and glyceraldehyde-3-phosphate dehydrogenase on aldolase action. 210 14

Fluorescence energy transfer measurements were implemented for demonstrating the specific character of the interaction between aldolase and glyceraldehyde-3-phosphate dehydrogenase. The enzymes, labeled with monobromobimane (donor) and fluorescein isothiocyanate (acceptor), respectively, were mixed into a cytosol preparation and energy transfer between the two fluorophores was observed to develop. This observation reflecting a contact between the two enzymes, suggests that despite the presence of a multitude of potential macromolecular partners glyceraldehyde-3-phosphate dehydrogenase and aldolase are capable of recognizing each other in the cytoplasm. The idea that in vivo associations of metabolically sequential enzymes may be of physiological benefits is consistent with this result.
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PMID:Fructose-1,6-bisphosphate aldolase preferentially associates to glyceraldehyde-3-phosphate dehydrogenase in a mixture of cytosolic proteins as revealed by fluorescence energy transfer measurements. 211 96

Partition equilibrium experiments have been used to characterize the interactions of erythrocyte ghosts with four glycolytic enzymes, namely aldolase, glyceraldehyde-3-phosphate dehydrogenase, phosphofructokinase and lactate dehydrogenase, in 5 mM sodium phosphate buffer (pH 7.4). For each of these tetrameric enzymes a single intrinsic association constant sufficed to describe its interaction with erythrocyte matrix sites, the membrane capacity for the first three enzymes coinciding with the band 3 protein content. For lactate dehydrogenase the erythrocyte membrane capacity was twice as great. The membrane interactions of aldolase and glyceraldehyde-3-phosphate dehydrogenase were mutually inhibitory, as were those involving either of these enzymes and lactate dehydrogenase. Although the binding of phosphofructokinase to erythrocyte membranes was inhibited by aldolase, there was a transient concentration range of aldolase for which its interaction with matrix sites was enhanced by the presence of phosphofructokinase. In the presence of a moderate concentration of bovine serum albumin (15 mg/ml) the binding of aldolase to erythrocyte ghosts was enhanced in accordance with the prediction of thermodynamic nonideality based on excluded volume. At higher concentrations of albumin, however, the measured association constant decreased due to very weak binding of the space-filling protein to either the enzyme or the erythrocyte membrane. The implications of these findings are discussed in relation to the likely subcellular distribution of glycolytic enzymes in the red blood cell.
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PMID:Interactions of glycolytic enzymes with erythrocyte membranes. 214 Feb 76

Isolated triadic proteins were employed to investigate the molecular architecture of the triad junction in skeletal muscle. Immunoaffinity-purified junctional foot protein (JFP), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), aldolase and partially purified dihydropyridine (DHP) receptor were employed to probe protein-protein interactions using affinity chromatography, protein overlay and crosslinking techniques. The JFP, an integral protein of the sarcoplasmic reticulum (SR) preferentially binds to GAPDH and aldolase, peripheral proteins of the transverse (T)-tubule. No direct binding of JFP to the DHP receptor was detected. The interactions of JFP with GAPDH and aldolase appear to be specific since other glycolytic enzymes associated with membranes do not bind to the JFP. The DHP receptor, an integral protein of the T-tubule, also binds GAPDH and aldolase. A ternary complex between the JFP and the DHP receptor can be formed in the presence of GAPDH. In addition, the DHP receptor binds to a previously undetected Mr 95 K protein which is distinct from the SR Ca2+ pump and phosphorylase b. The Mr 95 K protein is an integral protein of the junctional domain of the SR terminal cisternae. It is also present in the newly identified "strong triads" (accompanying paper). From these findings, we propose a new model for the triad junction.
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PMID:Molecular interactions of the junctional foot protein and dihydropyridine receptor in skeletal muscle triads. 215 17

1. The proportion of aldolase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) associated with the particulate fraction of a cell was measured in aestivating and non-aestivating Neobatrachus pelobatoides. 2. Reduced binding of these enzymes was found in the brain, indicating lower glycolytic flux. This was not correlated to metabolic rate suggesting that glycolytic rate was reduced in this tissue in the early stages of aestivation, possibly due to a change in fuel use. 3. Measurement of total enzyme levels showed that the liver of aestivating frogs had less GAPDH and less aldolase than non-aestivating frogs.
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PMID:Changes in enzyme binding and activity during aestivation in the frog Neobatrachus pelobatoides. 236 75


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