Processing of human cathepsin D in lysosomes in vitro. 1985

V Gieselmann, and A Hasilik, and K von Figura

The proteolytic maturation of cathepsin D polypeptides was studied in lysosomes isolated from metabolically labeled fibroblasts. In lysosomes isolated from fibroblasts labeled with [35S]methionine, 70-95% of labeled cathepsin D polypeptides were represented by a Mr = 47,000 polypeptide after a 20-min pulse and 75-min chase. When these lysosomes were incubated in vitro, up to 70% of the Mr = 47,000 polypeptide was processed to mature cathepsin D polypeptides. The processing was dependent on the integrity of the lysosomes, had an optimum between pH 6 and 7, and could be stimulated by dithiothreitol and ATP. The noncleavable ATP analogue, adenosine 5'-(beta, gamma-imido)triphosphate, and GTP, CTP, and UTP could not substitute for ATP. The ATP-dependent stimulation was associated with an acidification of lysosomes. It was inhibited by agents that dissipate the lysosomal pH gradient (carbonyl cyanide p-trifluoromethoxyphenylhydrazone, N,N'-dicyclohexylcarbodiimide, nigericin, NH4Cl). A stimulatory effect of ATP was observed also at pH 5.5. The stimulation at pH 5.5 was not associated with acidification of lysosomes and was resistant to protonophores. Inhibitors of lysosomal cysteine proteinases and N-ethylmaleimide inhibited the processing. In the presence of ATP the processing activity was partially protected from inhibition by N-ethylmaleimide. In conclusion, the maturation of cathepsin D in lysosomes depends on cysteine proteinases and is stimulated by the ATP-driven acidification of lysosomes. In addition, ATP stimulates maturation at pH 5.5 by a mechanism not involving the proton pump.

UI MeSH Term Description Entries
D008247 Lysosomes A class of morphologically heterogeneous cytoplasmic particles in animal and plant tissues characterized by their content of hydrolytic enzymes and the structure-linked latency of these enzymes. The intracellular functions of lysosomes depend on their lytic potential. The single unit membrane of the lysosome acts as a barrier between the enzymes enclosed in the lysosome and the external substrate. The activity of the enzymes contained in lysosomes is limited or nil unless the vesicle in which they are enclosed is ruptured or undergoes MEMBRANE FUSION. (From Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed). Autolysosome,Autolysosomes,Lysosome
D008970 Molecular Weight The sum of the weight of all the atoms in a molecule. Molecular Weights,Weight, Molecular,Weights, Molecular
D009550 Nigericin A polyether antibiotic which affects ion transport and ATPase activity in mitochondria. It is produced by Streptomyces hygroscopicus. (From Merck Index, 11th ed) Epinigericin,Pandavir
D011480 Protease Inhibitors Compounds which inhibit or antagonize biosynthesis or actions of proteases (ENDOPEPTIDASES). Antiprotease,Endopeptidase Inhibitor,Endopeptidase Inhibitors,Peptidase Inhibitor,Peptidase Inhibitors,Peptide Hydrolase Inhibitor,Peptide Hydrolase Inhibitors,Peptide Peptidohydrolase Inhibitor,Peptide Peptidohydrolase Inhibitors,Protease Antagonist,Protease Antagonists,Antiproteases,Protease Inhibitor,Antagonist, Protease,Antagonists, Protease,Hydrolase Inhibitor, Peptide,Hydrolase Inhibitors, Peptide,Inhibitor, Endopeptidase,Inhibitor, Peptidase,Inhibitor, Peptide Hydrolase,Inhibitor, Peptide Peptidohydrolase,Inhibitor, Protease,Inhibitors, Endopeptidase,Inhibitors, Peptidase,Inhibitors, Peptide Hydrolase,Inhibitors, Peptide Peptidohydrolase,Inhibitors, Protease,Peptidohydrolase Inhibitor, Peptide,Peptidohydrolase Inhibitors, Peptide
D002259 Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone A proton ionophore that is commonly used as an uncoupling agent in biochemical studies. Carbonyl Cyanide para-Trifluoromethoxyphenylhydrazone,FCCP,(4-(Trifluoromethoxy)phenyl)hydrazonopropanedinitrile,Carbonyl Cyanide p Trifluoromethoxyphenylhydrazone,Carbonyl Cyanide para Trifluoromethoxyphenylhydrazone,Cyanide p-Trifluoromethoxyphenylhydrazone, Carbonyl,Cyanide para-Trifluoromethoxyphenylhydrazone, Carbonyl,p-Trifluoromethoxyphenylhydrazone, Carbonyl Cyanide,para-Trifluoromethoxyphenylhydrazone, Carbonyl Cyanide
D002402 Cathepsin D An intracellular proteinase found in a variety of tissue. It has specificity similar to but narrower than that of pepsin A. The enzyme is involved in catabolism of cartilage and connective tissue. EC 3.4.23.5. (Formerly EC 3.4.4.23).
D004229 Dithiothreitol A reagent commonly used in biochemical studies as a protective agent to prevent the oxidation of SH (thiol) groups and for reducing disulphides to dithiols. Cleland Reagent,Cleland's Reagent,Sputolysin,Clelands Reagent,Reagent, Cleland,Reagent, Cleland's
D005033 Ethylmaleimide A sulfhydryl reagent that is widely used in experimental biochemical studies. N-Ethylmaleimide,N Ethylmaleimide
D005347 Fibroblasts Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules. Fibroblast
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man

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