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:3.4.23.5 (cathepsin D)
4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The localization of cathepsin D-like acid proteinase in the rat stomach and other tissues was studied, and its biochemical properties were compared with those of rat gastric cathepsin D (EC 3.4.23.5). Cathepsin D-like acid proteinase existed overwhelmingly in the mucosal layer and was hardly detected in the gastric juice. Its subcellular distribution profile was very similar to that of acid phosphatase, but not to that of pepsinogen. This proteinase-like enzyme activity was also found in rat splenic extract. These results strongly suggest that the proteinase is a lysosomal enzyme. In addition, cathepsin D-like acid proteinase demonstrated an in vitro transition of molecular species during storage at -30 degrees C. Although this molecular change was distinctive in ion-exchange column chromatography and susceptibility to some enzyme inhibitors, it was not accompanied by a significant decrease in molecular weight. To compare cathepsin D-like acid proteinase with ordinary cathepsin D, gastric cathepsin D was newly purified to apparent homogeneity in polyacrylamide gel electrophoresis. Its biochemical properties demonstrate that this is a true cathepsin D in rat gastric mucosa. Moreover, this cathepsin D activity was not abolished by treatment with antiserum specific to cathepsin D-like acid proteinase or pepsinogen. From these results, we can conclude that the proteinase is a lysosomal acid proteinase different from newly purified gastric cathepsin D.
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PMID:A comparative study of two kinds of cathepsin D-type proteinases from rat gastric mucosa. 406 86

Various biosynthetic forms of porcine spleen cathepsin D (Erickson, A. H. and Blobel, G. (1979) J. Biol. Chem. 254, 11771-11774), isolated by immunoprecipitation of in vivo- and in vitro-synthesized products, have been characterized by partial NH2-terminal sequence analysis. Two short lived and functionally distinct NH2-terminal sequence extensions, a "pre" sequence and a "pro" sequence, have been detected. Both sequence extensions are present in preprocathepsin D which is the primary translation product immunoprecipitated after translation of porcine spleen mRNA in a wheat germ cell-free system. Preprocathepsin D is not glycosylated and has an approximate Mr = 43,000. Its 20-residue pre sequence resembles the signal sequences of presecretory proteins in abundance of Leu residues (7 out of 20 residues). Addition of dog pancreatic microsomal vesicles to the translation system resulted in the cleavage of the pre sequence and yielded segregated and glycosylated procathepsin D (Mr = 46,000) that was indistinguishable from its in vivo-synthesized counterpart detected after pulse-labeling of cultured porcine kidney cells. Some of this in vivo-synthesized procathepsin D was secreted and persisted as such in the culture medium. The remainder was converted within a period of 15 min to 2 h to single chain cathepsin D (Mr = 44,000) by removal of a pro sequence which was estimated to be 44 residues. Its partial sequence showed considerable sequence homology to the 44-residue activation peptide of pepsinogen. It is possible, therefore, that the prosequence of procathepsin D serves as an activation peptide that keeps the enzyme inactive during intracellular transport to the lysosome. The enzymatically active single chain form of cathepsin D undergoes further cleavage into a light and a heavy chain (Mr = 15,000 and 30,000, respectively) over a period of 2-24 h after synthesis. The oligosaccharide moieties of procathepsin D and of the single chain and heavy chain forms of cathepsin D are cleaved by endoglycosidase H. Treatment of cells with tunicamycin arrests the biosynthetic pathway of cathepsin D at procathepsin D. The nonglycosylated procathepsin D is not proteolytically processed and its secretion is greatly inhibited.
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PMID:Biosynthesis of a lysosomal enzyme. Partial structure of two transient and functionally distinct NH2-terminal sequences in cathepsin D. 611 13

Precursors of cathepsin D and beta-hexosaminidase were isolated from secretions of human fibroblasts and their activity was studied with natural substrates. The immunoprecipitated precursor of cathepsin D, Mr 53000, was inactive with radioactive hemoglobin as substrate. At pH 3.8-4.2 an activation of the precursor took place, which was correlated by a reduction in size to Mr 51500. The observed cleavage of cathepsin D precursor in vitro resembles the autocatalytic activation of pepsinogen. The precursor of beta-hexosaminidase A is able to cleave the natural substrate GM2 ganglioside. This reaction, like that of the mature enzyme, depends on the presence of a protein activator, which interacts with the substrate and the enzyme.
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PMID:Lysosomal enzyme precursors in human fibroblasts. Activation of cathepsin D precursor in vitro and activity of beta-hexosaminidase A precursor towards ganglioside GM2. 621 95

Besides extracellular mammalian aspartic proteinases also intracellular proteinase cathepsin D is synthesized in the form of a precursor. The evidence is presented that cathepsin D zymogen (cathepsinogen D, procathepsin D) can be activated by a similar mechanism to that of pepsin, releasing an activation segment - peptide(s). The released peptide(s) show inhibitory activity towards cathepsin D and some other aspartic proteinases. The activation peptides released from bovine pepsinogen do not inhibit cathepsins D and E. The structure of different aspartic proteinases was studied by circular dichroism measurements. The binding of pepstatin causes conformational changes in the near UV CD spectrum.
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PMID:Aspartic proteinases: their activation and structural studies. 676 43

An assay for pepsin has been developed based on the fluorometric measurement of trichloroacetic acid-soluble peptides released from casein at pH 5.3. The increase in relative fluorescence was most sensitive in the range 10-50 micrograms pepsin/l and casein hydrolysis was not affected by the addition of up to a 1000-fold molar excess of pepsinogen. This assay has been used to measure the free and total acid proteinase content of biopsies (less than 5 mg) from different areas of the gastric mucosa of rat and man. Interference by the major lysosomal acid hydrolase, cathepsin D, could be eliminated by the differential stability of pepsin and cathepsin D at acid and neutral pH. The free acid proteinase activity of biopsies from the corpus were almost identical in these species whereas the total acid proteinase activity was approximately 5-fold greater in man.
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PMID:A sensitive fluorometric assay for the simultaneous estimation of pepsin and pepsinogen in gastric mucosa. 681 87

Lactoyl-pepstatin (an acylated tetrapeptide) is much more readily soluble in aqueous media than the more common isovaleryl- and acetyl-pepstatins (acylated pentapeptides). However, the K1 value for inhibition of cathepsin D by lactoyl-pepstatin at pH 3.5 is approx. 10(-7) M, some two to three orders of magnitude weaker than has been obtained previously for isovaleryl- or acetyl-pepstatins. One of the peptides released during activation of pig pepsinogen is known to be an effective inhibitor of pig pepsin, but it does not alter the activity of the similar aspartic proteinase, pig cathepsin D.
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PMID:The effects of lactoyl-pepstatin and the pepsin inhibitor peptide on pig cathepsin D. 711 18

The subcellular distribution and targeting of the non-lysosomal aspartic proteinase cathepsin E have been studied using mouse L cells and monkey Cos 1 cells that were transfected with cDNA encoding cathepsin E. The cathepsin E was retained in L cells for at least 20 h without significant degradation and its single N-linked oligosaccharide remained sensitive to endo-beta-N-acetyl-glucosaminidase H. When cathepsin E was overexpressed by transient transfection in Cos 1 cells, it was very slowly secreted into the media. The intracellular form of the enzyme contained a high mannose oligosaccharide which was processed to a complex type species upon secretion. In double label immunofluorescence studies, cathepsin E co-localized with cathepsin D-myc-KDEL, an endoplasmic reticulum (ER) marker. Subcellular fractionation on a Percoll density gradient showed that the cathepsin E co-migrated with membranous vesicles that were distinct from dense lysosomes. Only a trace amount of the enzyme was recovered in the soluble fraction. These findings indicate that in L cells and Cos 1 cells, the intracellular location of cathepsin E is the endoplasmic reticulum. To identify the protein sequences required for ER retention, we made chimeric proteins between cathepsin E and pepsinogen, an aspartic proteinase that is rapidly secreted by Cos 1 cells. We found that amino acids 1-48 of cathepsin E are important for its retention in the ER. Within this region, Cys7, which is involved in covalent dimer formation, plays a significant role in the retention.
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PMID:Subcellular localization and targeting of cathepsin E. 798 70

The current investigation examines the changes in the expression of pepsinogen C and cathepsin D and E genes in the gastric mucosa during aging and following physiological stimuli of fasting and refeeding. Northern blot analysis of gastric mucosal RNA, isolated from overnight fasted 6-, 12-, and 24-month-old male Fischer 344 rats, revealed that although steady-state mRNA levels of each of these protease remained essentially unchanged between 6 and 12 months of age, in 24-month-old rats the levels were decreased by about 60%, when compared with their younger counterparts. Interestingly, the relative concentration of beta-actin mRNA--but not 18s rRNA--in 12- and 24-month-old rats was also decreased by 23% and 37%, respectively, when compared with 6-month-old animals. In the next set of experiments, groups of young (3 month) and aged (24 month) rats were either fed throughout (controls) or fasted for 48 h and then fed for 6 h and 24 h. Gastric mucosal RNA from each group was assayed for steady-state mRNA levels of pepsinogen C and cathepsin D. Results showed that whereas in young rats fasting decreased pepsinogen C and cathepsin D mRNAs by 80-85%, in aged rats only pepsinogen mRNA was significantly decreased (45%), when compared with the corresponding initial fed controls. In both age groups, refeeding increased pepsinogen C mRNA concentration essentially to the respective initial fed levels. In contrast, cathepsin D mRNA levels in the gastric mucosa of aged rats was affected neither by fasting nor by refeeding. Our current data show that aging not only diminishes the expression of protease genes in the gastric mucosa, but also the expression of one of its structural genes, beta-actin. In addition, responsiveness of these protease genes to the physiological stimuli of fasting and refeeding is also attenuated by aging. We postulate that these age-related changes may in part be due to diminished differentiation of gastric mucosal cells.
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PMID:Expression of protease genes in the gastric mucosa during aging. 834 96

B lymphocytes from patients with I-cell disease (ICD) maintain normal cellular levels of lysosomal enzymes despite a deficiency of the enzyme UDP-N-acetylglucosamine: lysosomal enzyme N-acetylglucosamine-1-phosphotransferase. We find that an ICD B lymphoblastoid cell line targets about 45% of the lysosomal protease cathepsin D to dense lysosomes. This targeting occurs in the absence of detectable mannose 6-phosphate residues on the cathepsin D and is not observed in ICD fibroblasts. The secretory protein pepsinogen, which is closely related to cathepsin D in both amino acid sequence and three-dimensional structure, is mostly excluded from dense lysosomes, indicating that the lymphoblast targeting pathway is specific. Carbohydrate residues are not required for lysosomal targeting, since a non-glycosylated mutant cathepsin D is sorted with comparable efficiency to the wild type protein. Analysis of a number of cathepsin D/pepsinogen chimeric proteins indicates that an extensive polypeptide determinant in the cathepsin D carboxyl lobe can confer efficient lysosomal sorting when introduced into the pepsinogen sequence. This determinant overlaps but is not identical to the recognition marker for phosphotransferase. These results indicate that a specific protein recognition event underlies Man-6-P-independent lysosomal sorting in ICD lymphoblasts.
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PMID:Mannose 6-phosphate-independent targeting of lysosomal enzymes in I-cell disease B lymphoblasts. 840 10

Human procathepsin D was isolated from medium of human breast cancer cell line ZR-75-1 potentiated with estrogen. The isolation involved both immunoaffinity chromatography and ion-exchange chromatography. The affinity chromatography employed polyclonal antibodies raised against a synthetic activation peptide of human cathepsin D. We have started preliminary crystallization trials using the isolated material. A model of human procathepsin D was also built using coordinates of human cathepsin D and pig pepsinogen. The model aids understanding of multiple roles played by activation peptides of aspartic proteinases and will be used as a starting model for molecular replacement.
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PMID:Human procathepsin D: three-dimensional model and isolation. 854 Mar 27


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