Three parameters participating in the specific control of proteolytic processes in intact yeast cells are discussed: (1) different substrate specificity of the yeast proteinases A and B, and carboxypeptidase Y when tested with yeast enzymes as substrate, (2) three types of macro molecular inhibitors from yeast specifically inhibiting the three pro teinases, (3) subcellular localization of the proteinases in the vacu oles and of the inhibitors in the cytosol. Mechanisms of a selective proteolysis of single enzymes or a group of enzymes dependent on chan ges in the physiological conditions are discussed. References Betz, H., Hinze, H., Holzer, H.: Isolation and properties of two inhibitors of proteinase B from yeast. J. Bioi. Chem. 249, 4515-4521 (1974) Cabib, E., Farkas, V.: The control of morphogenesis: An enzymatic mechanism for the initiation of septum formation in yeast. Proc. Nat. Acad. Sci. U.S. 68, 2052-2056 (1971) Cabib, E., Keller, F.A.: Chitin and yeast budding. J. Bioi. Chem. 246, 167-173 (1971) Cabib, E., Ulane, R.: Chitin synthetase activating factor from yeast, a protease. Biochem. Biophys. Res. Commun. 50, 186-191 (1973) Hasilik, A.: Inactivation of Chitin Synthase in Saccharomyces cerevisiae. Arch. Microbiol. 101, 295-301 (1974) Hasilik, A., Holzer,~: PartiCipation of the tryptophan synthase inactivating system from yeast in the activation of chitin synthase. Biochem. Biophys. Res.

Inhalt
Interconversion in the Control of Glycogen Metabolism.- Concerted Regulation of Glycogen Metabolism and Muscle Contraction.- The Regulation of Glycogen Metabolism by Multivalent Phosphorylation.- Localization and Turnover of Phosphorylase Kinase in Rabbit Skeletal Muscle.- Probes in Studying the Architecture of Interconvertible Enzymes.- Hybridphosphorylases.- Purification and Properties of E. coli Maltodextrin Phosphorylase.- Excited-State vs Ground-State Structure of the Pyridoxal 5';-Phosphate Site in Glycogen Phosphorylase b.- Structure and Function of Regulatory Sites.- The Use of an Alternative Substrate as a Model System for the Study of Phosphorylase Kinase.- Restriction of the Allosteric Properties of Phosphorylase b by Single Links of a Bifunctional Reagent.- Interconvertible Forms of a cAMP-Dependent Protein Kinase from Bovine Cardiac Muscle.- Glycogen Synthase and Its Interconversion.- Studies on Glycogen Synthase and Its Control by Hormones.- Conversion into I Form of Glycogen Synthetase from Frog Muscle and Scallop Muscle.- Regulation of Adipose Tissue Glycogen Synthetase Activation.- The Phosphatases - Specific or Not.- Rabbit-Liver Glycogen Synthase: Properties and Interconversion by Phosphorylation and Dephosphorylation.- Recent Investigations on the Control of Glycogen Metabolism in the Liver.- Pyruvate Dehydrogenase - Assembly, Function and Control.- Structure and Regulation of the Mammalian Pyruvate Dehydrogenase Complex.- Metabolic Interconversion of the Pyruvate Dehydrogenase Complex as Related to the Mitochondrial Energy State.- Regulation of Pyruvate Dehydrogenase by End Product Inhibition and by Phosphorylation.- Adenylylation, ADP-Ribosylation and Phosphorylation as Regulatory Signals.- Metabolic Regulation of Coupled Covalent ModificationCascade Systems.- ADP-Ribosylation of Elongation Factor 2 by Pseudomonas aeruginosa Exotoxin A and by Diphtheria Toxin.- Protein-ADP-Ribosylating System of Mitochondria.- RNA Polymerase Modifications after T-Phage Infections of E. coli.- Specific Proteolysis - A Regulatory Device?.- Characteristics and Functions of Proteinases and Proteinase Inhibitors in Yeast.- Specific Proteolytic Modification of Rabbit Liver Fructose Biphosphatase under Gluconeogenic Conditions.- Regulation of Protein Turnover and the Role of Lysosomes.- In situ vs. in vivo Studies.- Study of Enzyme Activity in Animal Cells in situ.- The Glycolytic Pathway in Yeast. Study under in situ Conditions.- Interconversion of Rat Liver Phosphofructokinase by Phosphorylation and Dephosphorylation.- Unusual Modulations of Enzyme Action.- Histidine Decarboxylase from Lactobacillus 30a: Nature of Conversion of Proenzyme to Active Enzyme.- Reductive Generation of Vicinial Dithiols by Photosynthetic Electron Transport System is Involved in Light-Regulation of Chloroplast Enzyme Activity.- The Accumulation of Faulty Enzyme Molecules in Aging Cells.