The Enzymes of Biological Membranes

of Volume 2.- 14. Ether-Linked Glycerolipids and Their Bioactive Species: Enzymes and Metabolic Regulation.- I. Introduction.- II. Ether Lipid Precursors.- A. Acyl-CoA Reductase.- B. Acyl-CoA:Dihydroxyacetone-P Acyltransferase (EC 2.3.1.42).- III. Biosynthesis of Alkyl and Alk-l-enyl (Plasmalogen) Glycerolipids.- A. Alkyldihydroxyacetone-P Synthase.- B. NADPH:Alkyldihydroxyacetone-P Oxidoreductase.- C. NADPH: Alky ldihydroxyacetone Oxidoreductase.- D. ATP: 1 –Alkyl-sn-glycerol Phosphotransferase (EC 2.7.1.93).- E. ATP:Alkyldihydroxyacetone Phosphotransferase (EC 2.7.1.84).- F. Acyl- oA:l-Alkyl-2-lyso-sn-glycero-3-P Acyltransferase (Ec 2.3.1.63).- G. Acyl-CoA:1-Alkyl-2-acyl-sn-glycerol Acyltransferase.- H. Acyl-CoA:Alkylglycerol Acyltransferase.- I. l-Alkyl-2-acyl-sn-glycerol.CPD-Choline (or CDP-ethanolamine) Choline(ethanolamine)phosphotransferase.- J. -Alk-1’-enyl-2-acyl-sn-glycerol:CDP-Choline (or CDP-ethanolamine) Choline(ethanolamine)phosphotransferase.- K. 1 -Alkyl-2-acyl-sn-glycero-3-hosphoethanolamine esaturase (EC 1.14.99.19).- L. Acyl-CoA:l-Radyl-2-lyso-sn-glycero-3-phosphocholine (or hosphoethanolamine) Acyltransferase (EC 2.3.1.25).- M. Ca2+-Dependent Base Exchange Reactions.- IV. Biologically Active Alkyl Phospholipids (Platelet-ActivatingFactor).- A. Acetyl-CoA: l-Alkyl-2-lyso-sn-glycero-3-phosphocholine Acetyltransferase.- B. l-Alkyl-2-acetyl-sn-glycerol:CDP-Choline Cholinephosphotransferase.- C. 1-Alkyl-2-acetyl-sn-glycero-3- phosphocholine Acetylhydrolase.- D. Pte • H4-Dependent Alkyl Monooxygenase (EC 1.14.16.5).- V. Catabolism of Alkyl and Alk-l-enyl (Plasmalogen)Glycerolipids 31.- A. NAD+: Fatty Alcohol Oxidoreductase.- B. Pte • H4-Dependent Alkyl Monooxygenase (EC 1.14.16.5).- C. Alkenylglycerophosphocholine(ethanolamine)hydrolase (EC 3.3.2.2) Plasmalogenase) 33 • D. Phosphohydrolases.- D. Phosphohydrolases.- E. Lipases.- F. Phospholipases.- VI. Assessment of the Prominence of the Acyl-DHAP and Ether Lipid Pathways in Complex Systems.- VII. Regulation of Ether Lipid Metabolic Pathways.- A. Turnover of Ether-Linked Glycerolipid Species.- B. Ether Lipid Precursors and Alkyl Glycerolipids.- C. Alk-l-enyl Glycerolipids (Plasmalogens).- D. Bioactive Alkyl Phospholipids.- References.- 15. Fatty Acid Synthetases of Eukaryotic Cells.- I. Introduction.- II. Fatty Acid Synthetases of Eukaryotes.- A. Animal Fatty Acid Synthetases.- B. Yeast Fatty Acid Synthetase.- III. Component Activities.- A. Acetyl and Malonyl Transacylases.- B. ?-Ketoacyl Synthetase (Condensing Enzyme).- C. (3-Ketoacyl and Enoyl Reductases.- D. ?-Hydroxyacyl Dehydratase.- E. Palmitoyl Thioesterase.- IV. Mechanism of Action of Fatty Acid Synthetase.- A. Animal.- B. Yeast.- References.- 16. Properties and Function of Phosphatidylcholine Transfer Proteins.- I. Introduction.- II. Phosphatidylcholine Transfer Protein from Bovine Liver.- A. Introductory Remarks.- B. Mode of Action.- C. Molecular Aspects.- D. oncluding Remarks.- III. Phosphatidylcholine Transfer Protein from Rat Liver.- A. Some Characteristics.- B. Levels in Various Tissues.- IV. General Conclusions.- References.- 17. Carnitine Palmitoyltransferase and Transport of Fatty Acids.- I. Introduction.- A. Metabolic Fate of Long-Chain Fatty Acids.- B. Role of Carnitine in Fatty Acid Oxidation.- C. Carnitine Acyltransferases.- D. Carnitine Esther Hydrolase.- II. Assays.- A. General Comments.- B. Isotope-Exchange Method.- C. Forward Reaction.- D. Backward Reaction.- III. Mitochondrial Localization.- A. Intracellular Localization 143.- B. Functional Studies in Mitochondria.- C. Mitochondrial Membrane Fractionation.- D. Substrate-Specificity Studies in Mitochondria.- IV. Purification and Characterization of Carnitine Palmitoyltransferase.- A. Purified Carnitine Palmitoyltransferase.- B. Relationship of Purified Enzymes to Functional Localization in Mitochondria.- C. Properties of Membrane-Bound Carnitine Palmitoyltransferase.- D. Reversibility of Carnitine Palmitoyltransferase B.- V. Carnitine Palmitoyltransferase and Mitochondrial Fatty Acid Oxidation.- A. Is Carnitine Palmitoyltransferase Rate-Limiting Step for Fatty Acid Oxidation? The Role of Malonyl-CoA.- B. Carnitine Palmitoyltransferase A.- VI. Carnitine—Acylcarnitine Translocase.- VII. Carnitine Palmitoyltransferase: Substrate Specificity.- A. Carnitine.- B. Acylcarnitine and Acyl-CoA.- VIII. Inhibitors of Carnitine Palmitoyltransferase.- A. 2-Tetradecylglycidic Acid.- B. 2-Substituted Oxiran-2-Carbonyl- CoA Esters.- C. 1-Pyrenebutyryl-CoA.- D. Carba-analogue of Palmitoyl-CoA.- E. Acyl-d-carnitine.- F. 2-Bromoacyl Derivatives.- IX. Changes in Tissue Enzymatic Activity.- A. Increases in Carnitine Palmitoyltransferase Activity.- B. Decreases in Carnitine Palmitoyltransferase Activity.- C. Changes in Distribution of CPT-A and CPT-B.- D. Metabolic Myopathies Associated with Carnitine Palmitoyltransferase Deficiency.- X. Summary and Future.- References.- 18. Membrane-Bound Enzymes of Cholesterol Biosynthesis: Resolution and Identification of the Components Required for Cholesterol Synthesis from Squalene.- I. Introduction.- A. Scope.- B. Objectives.- II. Squalene Synthetase.- A. Purification Methods.- B. Mechanism.- III. Squalene Oxidase.- A. Squalene Epoxidase.- B. Squalene 2,3-Oxide-lanosterol Cyclase.- C. Cytosolic Protein Effectors.- D. Mechanism.- IV. Oxidative Demethylation of C-32 from Lanosterol.- A. Metabolite Identification.- B. Cytochrome P-450 Involvement.- V. Steroid 14-Reductase.- A. Description of Enzymatic Activity.- B. Solubilization.- VI. Oxidative Demethylation of 4,4-Dimethyl Sterols.- A. Methyl Sterol Oxidase.- B. Decarboxylase.- C. 3-Ketosteroid Reductase.- D. Cytosolic Protein Effectors.- VII. ?8 ?7 Isomerase.- A. Purification Data.- B. Mechanism.- VIII. ?5-Desaturase.- A. Purification and Reconstitution.- B. Mechanism.- C. Cytosolic Protein Effectors.- IX. 7-Dehydrocholesterol ?7 -Reductase.- A. Purification Data.- B. Cytosolic Protein Effectors.- C. Mechanism.- X. A24-Sterol 24-Reductase.- A. Purification Data.- B. Mechanism.- XI. Coordinate Control Mechanisms of Sterol Synthetic Enzymes.- A. HMG-CoA Reductase.- B. Multilevel Control.- C. Soluble-Protein Involvement.- References.- 19. Membrane-Bound Enzymes in Plant Sterol Biosynthesis.- I. Introduction.- II. Initial Stages.- A. HMG-CoA Reductase (EC 1.1.1.34).- B. Farnesyl Pyrophosphate (EC 2.5.1.1): Squalene Synthesis.- III. Cyclization of Squalene.- A. Squalene Monooxidase (EC 1.14.99.7).- B. Oxidosqualene Cyclases.- IV. Formation of Sterols from Cycloartenol.- A. S-Adenosylmethionine: ?24-Triterpene Methyl Transferase.- B. Cycloeucalenol:Obtusifoliol Isomerase 217.- C. S-Adenosylmethionine:24-Methylenelophenol Transferase.- D. ?25-Sterol Reductase.- V. Glycosylation of Phytosterols and Acylation of Sterol Glycosides.- A. Uridine Diphosphate Glucose:Sterol Transglucosylase.- B. Phosphatidylethanolamine: Sterol Transacylase.- VI. Esterification of Sterols.- A. Diacylglycerol:Sterol Acyltransferase.- VII. Hydrolysis of Sterol Esters.- VIII. Summary.- References.- 20. Glycosyltransferases Involved in the Biosynthesis of Protein-Bound Oligosaccharides of the Asparagine-N-Acetyl-D-Glucosamine and Serine (Threonine)-N-Acetyl-D-Galactosamine Types.- I. Introduction.- II. Asn-GlcNAc Oligosaccharide Structure.- III. Asn-GlcNAc Oligosaccharide Initiation and Processing.- IV. Synthesis of Nonbisected Bi-Antennary Complex N-Glycosyl Oligosaccharides.- A. UDP-GlcNAc:?-D-Mannoside (GlcNAc to Man? 1-3) ßl-2-GlcNAc- Transferase I.- B. GlcNAc-Transferase-I-Dependent ?3/6-Mannosidase(s) (Mannosidase II).- C. UDP-GlcNAc:?-D-Mannoside (GlcNAc to Man? l-6) ßl-2-GlcNAc-Transferase II.- D. UDP- Gal:GlcNAc ß1-4-Galactosyltransferase.- E. CMP-NeuNAc:Galßl- 4GlcNAc ?2-6-Sialyltransferase.- F. CMP-NeuNAc:Galßl-3(4)GlcNAc ?2-3-Sialyltransferase.- G. GDP-Fuc:ß-N-Acetylglucosaminide (Fuc to Asn-Linked GlcNAc) ? l-6-Fucosyltransferase.- H. GDP-Fuc:ß- Galactoside ? 1-2-, ? 1-3-, and ? 1-4-Fucosyltransferases.- V. Synthesis of Bisected Oligosaccharides.- A. UDP-GlcNAc:GnGn (GlcNAc to Manßl-4) ßl-4-GlcNAc-Transferase III.- B. Hybrid Oligosaccharide Synthesis 249.- C. Elongation Reactions on Bisected Oligosaccharides.- VI. Synthesis of Tri-Antennary N-Glycosyl Oligosaccharides.- A. UDP-GlcNAc:GnGn (GlcNAc to Man? l-3) ßl-4-GlcNAc-Transferase IV.- B. UDP-GlcNAc:GnGn (GlcNAc to Man) ßl-6-GlcNAc- Transferase V.- C. Elongation of Tri- and Tetra-Antennary Oligosaccharides.- VII. Ser(Thr)-GalNAc Oligosaccharide Structures.- VIII. Initiation of Ser(Thr)-GalNAc Oligosaccharide Synthesis.- IX. Synthesis of Ser(Thr)-GalNAc Oligosaccharides.- A. Assembly of Oligosaccharides with Core Class 1.- B. Synthesis of Oligosaccharides with Core Class 2.- C. Synthesis of Oligosaccharides with Core Classes 3 and 4.- X. Concluding Remarks: Control of Synthesis.- References.- 21. Biosynthesis of the Bacterial Envelope Polymers Teichoic Acid and Teichuronic Acid.- I. Introduction.- II. Teichoic Acid Structure.- A. Poly(Alditol Phosphate.- B. Polymers with Glycosyl Residues as Part of the Chain.- C. Sugar 1-Phosphate Polymers.- D. Attachment of Wall Teichoic Acids to Peptidoglycan.- III. Biosynthesis of Teichoic Acids.- A. Synthesis of Nucleotide Precursors.- B. Biosynthesis of Poly(Alditol Phosphate) Polymers.- C. Biosynthesis of Teichoic Acids with Sugar Residues in the Main Chain.- D. Addition of Glycosyl and Alanyl Substituents.- IV. Teichuronic Acid Structure and Synthesis.- V. Incorporation of Teichoic Acid and Teichuronic Acid into the Cell Wall.- VI. Synthesis of Membrane Lipoteichoic Acid.- VII. Mode of Action of the Enzymes in the Membrane.- VIII. Regulation of Synthesis of Teichoic and Teichuronic Acids.- References.- 22. The Major Outer Membrane Lipoprotein of Escherichia coli: Secretion, Modification, and Processing.- I. Introduction.- II. The Structure of Lipoprotein and Its Gene.- III. Secretion of Lipoprotein across the Cytoplasmic Membrane.- A. Characterization of Prolipoprotein, the Secretory Precursor of Lipoprotein.- B. Role of the Lipoprotein Signal Peptide in Translocation across the Cytoplasmic Membrane.- C. Analysis of Mutations Involving the Prolipoprotein Signal Peptide.- IV. Modification and Processing of Lipoprotein.- A. Formation of Glyceryl Prolipoprotein 320.- B. Formation of Glyceride Prolipoprotein.- C. Proteolytic Cleavage of the Prolipoprotein Signal Peptide.- D. Acylation of Apolipoprotein.- E. Peptidoglycan Attachment of Mature Lipoprotein.- V. Conclusions.- References.- 23. Anchoring and Biosynthesis of a Major Intrinsic Plasma Membrane Protein: The Sucrase-Isomaltase Complex of the Small-Intestinal Brush Border.- I. Introduction.- II. Gross Positioning.- III. Detailed Positioning.- IV. Pro-Sucrase-Isomaltase, a Fully Enzymatically Active Precursor.- V. Biosynthesis of Pro-SI.- References.- 24. Multifunctional Glucose-6-Phosphatase: A Critical Review.- I. Introduction.- II. Reviews.- III. Newer Methods of Assay.- IV. Purification and Physical Characteristics.- V. Recent Mechanistic Studies.- VI. Newer Reports on the Distribution of Glucose-6-phosphatase.- VII. Zonal Distribution of the Hepatic Enzyme.- VIII. Regulation of Glucose-6-phosphatase Activities.- A. Inhibitors and Activators.- B. Control by Protein Phosphorylation-Dephosphorylation.- C. Control by in Vivo Perturbations.- D. Newer Techniques for Study of the Bioregulation of Glucose-6-phosphatase.- IX. Membrane Phospholipids and Glucose-6-phosphatase Action.- A. Synopsis of Relevant Earlier Work.- B. Recent Studies of Phospholipid Requirements.- C. Some Tentative Conclusions.- X. The Molecular Basis of Latency.- A. Historical Considerations.- B. The “Membrane-Sidedness” and “Constrained-Unconstrained Conformer” Hypotheses.- C. The Translocase-Catalytic Unit Hypothesis.- D. A Proposed Synthesis of the Membrane Conformational and Translocase-Catalytic Unit Concepts.- E. Behavior of the Enzyme in Intact Endoplasmic Reticulum of Isolated Permeable Hepatocytes.- F. Some Tentative Conclusions.- XI. Metabolic Considerations.- A. Muscle.- B. Brain.- C. Liver.- References.- 25. The ß-Adrenergic Receptor: Elucidation of Its Molecular Structure.- I. Historical Perspective.- II. Adrenergic Receptors and Adenylate Cyclase.- III. Molecular Components of Adrenergic Responsive Adenylate Cyclase Systems.- IV. Purification of ß-Adrenergic Receptors.- A. Solubilization of ß-Adrenergic Receptors.- B. Affinity Chromatography of ß-Adrenergic Receptors.- V. Molecular Identification of ß-Adrenergic Receptors.- A. Visualization of the Purified Receptor Peptide(s).- B. Photoaffinity Labeling of ß-Adrenergic Receptors.- C. Radiation Inactivation Studies of ß-Adrenergic Receptors.- VI. Summary and Perspectives.- References.- 26. Ionic Channels and Their Metabolic Control.- I. Introduction.- II. Peculiarities of Different Types of Membrane Ionic Channels.- A. Selectivity.- B. Sensitivity to Changes in Intracellular Ionic Composition.- C. [Ca2 +]i-Activated Channels.- III. Metabolic Regulation of Ionic Channels.- A. Activity of Calcium Channels Dependent on Metabolism.- B. Data on Metabolic Dependence of the Activity of Ca-Dependent Potassium Channels.- C. Possible Metabolic Dependence of the Activity of Other Types of Ionic Channels.- IV. Conclusion.- References.