Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.5 (cathepsin D)
 4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The propeptides of lysosomal enzymes have been implicated in membrane association and mannose 6-phosphate-independent sorting to the lysosome (Rijnboutt, S., Aerts, H., Geuze, H. J., Tager, J. M., and Strous, G. J. (1991) J. Biol. Chem. 266, 4862-4868; McIntyre, G. F., and Erickson, A. H. (1991) J. Biol. Chem. 266, 15438-15445). In this report, the function of the propeptide of procathepsin D in sorting to the lysosome was directly assessed using a cathepsin D deletion mutant lacking the propeptide, and using a chimeric cDNA encoding the cathepsin D propeptide fused to the secretory protein alpha-lactalbumin. Proteins encoded by these cDNAs were expressed in mouse Ltk- cells and in human hepatoma Hep G2 cells, and then immunoprecipitated and analyzed by SDS-polyacrylamide gel electrophoresis. The deletion mutant was glycosylated but was rapidly degraded in a chloroquine-independent fashion and did not assume an active conformation. Thus the propeptide appeared to be necessary for correct folding. The chimeric protein was glycosylated and secreted. The coincidence of complex oligosaccharide modification and secretion of the chimeric protein suggested that it was slowly released from the endoplasmic reticulum and rapidly passed through the cell to the extracellular compartment. This was confirmed by immunofluorescent localization of the proteins. The data indicated that the propeptide appeared to be necessary for folding of cathepsin D but, unlike the yeast vacuolar propeptides, was not sufficient to direct a secretory protein to the lysosome in fibroblasts or in epithelial cells.
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PMID:The role of the cathepsin D propeptide in sorting to the lysosome. 140 Apr 84

A cDNA clone containing the entire coding region for bovine pre-alpha-lactalbumin (LA) together with 27 base pairs of 5'-noncoding and 268 base pairs of 3'-noncoding sequences was isolated from a bovine mammary cDNA plasmid library in the Okayama-Berg vector system using a synthetic oligonucleotide probe and sequenced. The coding segment for mature LA was subcloned into the T7 expression system of Studier and co-workers (Studier, F.W., and Moffatt, B.A. (1986) J. Mol. Biol. 189, 113-130; Rosenberg, A.H., Lade, B.N., Chui, D.S., Lin, S.W., Dunn, J.J., and Studier, F.W. (1987) Gene (Amst.) 56, 125-135) and expressed as a 21-kDa fusion protein that consisted of the mature bovine LA sequence connected to the NH2-terminal 50 residues of human cathepsin D by a linker sequence containing protease cleavage sites. This fusion protein was expressed in an insoluble form and accumulated to about 50% of the total bacterial protein within 3 h after induction of T7 RNA polymerase synthesis. The protein was solubilized, purified by gel filtration, and converted to an active form by treatment with mixtures of reduced and oxidized glutathione in the presence of Ca2+. The maximum specific activity of the fusion protein was about 25% of that of native LA, suggesting that the attachment of an NH2-terminal extension sterically hinders but does not prevent the interaction with galactosyltransferase. The extension also does not block the binding of the regulatory Ca2+ ion that is required for folding from the reduced denatured state. Trypsin cleaved the folded fusion protein specifically at a Lys-Glu bond at the junction with the mature LA sequence to give a product indistinguishable in structure and activity from native LA.
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PMID:Recombinant bovine alpha-lactalbumin obtained by limited proteolysis of a fusion protein expressed at high levels in Escherichia coli. 268 74

Cathepsin D is an indigenous aspartic proteinase in bovine milk. By competitive enzyme-linked immunosorbent assay the amount of immunoreactive cathepsin D and procathepsin D in bovine skim milk was estimated to be 0.4 microgram/ml. Immunoreactive cathepsin D purified from whey consisted of a small fraction of mature cathepsin D, but the major form was the proenzyme procathepsin D. A preparation of bovine milk procathepsin D was, like mature cathepsin D, able to degrade purified alpha s1-, alpha s2-, beta- and kappa-casein and alpha-lactalbumin, while beta-lactoglobulin was resistant to cleavage. The cleavage sites in these proteins were determined and compared with those of chymosin. Cathepsin D was capable of generating the alpha s1-I, beta-I, beta-II and beta-III fragments originally described from the action of chymosin on the respective caseins, and these fragments were subjected to further proteolysis. Cathepsin D was also able to liberate the caseinomacropeptide from purified kappa-casein, and to coagulate bovine skim milk. This demonstrated that milk contains an indigenous coagulation enzyme present mainly in the whey fraction.
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PMID:Bovine milk procathepsin D and cathepsin D: coagulation and milk protein degradation. 865 37

The objective of the present study was to determine the effect of high pressure (HP) processing (200, 450 and 650 MPa) at various temperatures (20, 40 and 55 degrees C) on the total plasmin plus plasminogen-derived activity (PL), plasminogen activator(s) (PA) and cathepsin D activities and on denaturation of major whey proteins in bovine milk. Data indicated that transfer of both PL and PA from the casein micelles to milk serum occurred at all pressures utilized at room temperature (20 degrees C). In addition to the transfer of PL and PA from micelles, there were reductions in activities of PL (16-18%) and PA (38-62%) for the pressures 450 and 650 MPa, at room temperature. There were synergistic negative effects between pressure and temperature on residual PL activity at 450 and 650 MPa and on residual PA activity only at 450 MPa. Cathepsin D activity in the acid whey from HP-treated milk was in general baroresistant at room temperature. The residual activity of cathepsin D decreased significantly at 650 MPa and 40 degrees C and at the pressures 450 and 650 MPa at 55 degrees C. Synergistic negative effects on the amount of native beta-lactoglobulin were observed at 450 and 650 MPa and on the amount of native alpha-lactalbumin at 650 MPa. There were significant correlations between enzymatic activities (PL, PA and cathepsin D) and the residual native beta-lactoglobulin and alpha-lactalbumin in bovine milk. In conclusion, HP significantly affected the activity of indigenous proteolytic enzymes and whey protein denaturation in bovine milk. Reduction in activity of indigenous enzymes (PL, PA and cathepsin D) and transfer of PL and PA from the casein to milk serum induced by HP is expected to have a profound effect on cheese yield, proteolysis during cheese ripening and quality of UHT milk during storage.
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PMID:Effect of high-pressure treatment at various temperatures on indigenous proteolytic enzymes and whey protein denaturation in bovine milk. 1851 57