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

In addition to their general function in cellular homeostasis, thyroid lysosomes play an essential role in the biosynthesis of thyroid hormones by cleaving the macromolecular prohormone, thyroglobulin. In the present work, we have attempted to determine whether the enzyme composition of thyroid lysosomes differs from that of lysosomes from other tissues. Lysosomal enzymes, cathepsin D, beta-D-galactosidase, beta-D-glucosidase, alpha-D-mannosidase, alpha-L-fucosidase, hexosaminidase, and arylsulfatase A and B, were assayed in crude fractions from various pig tissues, heart, brain, liver, kidney, thyroid, adrenals, ovary, and spleen. It appeared that the specific activity of arylsulfatase A was at least 20 times higher in the thyroid than in most other tissues. Thyroid lysosomes purified by isopycnic centrifugation on Percoll gradients contained two major polypeptides with apparent molecular weights of 58,000 and 54,000 representing about 30% of the total protein. These polypeptides were glycosylated and were exclusively found in the intralysosomal soluble fraction obtained by osmotic pressure-dependent lysis. By fractionating intralysosomal soluble proteins by velocity sedimentation on sucrose gradients or gel permeation chromatography we identified a thyroid arylsulfatase A holoenzyme which corresponds to a 120,000 Mr species. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses of the gradient or column fractions showed that the 120-kDa protein peak with arylsulfatase A activity essentially contained the 58- and 54-kDa polypeptides in equivalent amounts. In conclusion, arylsulfatase A, a heterodimer of 120 kDa composed of two nonidentical subunits, is the major protein component of thyroid lysosomes. The superabundance of this protein in purified thyroid lysosomes is related to the very high specific activity of the enzyme in the thyroid as compared to other tissues.
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PMID:Evidence for the presence of a very high concentration of arylsulfatase A in the pig thyroid: identification of arylsulfatase A subunits as the two major glycoproteins in purified thyroid lysosomes. 256 93

Isolated perfused liver and cultures of rat hepatocytes were assessed for the quantitative evaluation of hepatotoxicity. Release of de novo biosynthesized plasma proteins and acid hydrolases into perfusion or culture media was taken as an indication of the integrity of hepatocytes in both systems. The activities of six acid hydrolases, alpha-L-fucosidase, alpha-D-galactosidase, beta-D-galactosidase, beta-D-N-acetylgalactosaminidase, beta-D-N-acetylglucosaminidase, and cathepsin D, were assayed in collagenase-segregated hepatocytes and in monolayer cultures of rat liver cells obtained via collagenase perfusion of rat liver. In situ, liver perfusion with collagenase led to a loss of 45 +/- 5% of the total acid hydrolase activity in the mitochondrial-lysosomal pellet of the liver cells with concomitant increase of these enzymes in the cytosol. In monolayer cultures over a period of 30 h, increased activity of cathepsin D, beta-D-galactosidase, and beta-D-N-acetylglucosaminidase in the mitochondrial-lysosomal pellet and the cytosol fraction was evident with concurrent biosynthesis of plasma proteins. The use of radioactive tracing techniques with the isolated perfused liver revealed that the rate of catabolism of intracellular protein was approximately 5 times that of plasma protein synthesis. Both methods described here are suitable for the study of the effects of toxins on the function of hepatocytes.
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PMID:Study of hepatotoxicity in isolated perfused liver versus cultures of rat hepatocytes. 291 36

We have examined the activity and distribution of cathepsin D (EC 3.4.23.5), a major renal lysosomal endoproteinase, in the various anatomical and functional areas of normal rat kidney. Cathepsin D-like activities (delta A280/h per mg of protein) in normal rat tissues were: cortex, 0.78 +/- 0.05, n = 37; medulla, 0.62 +/- 0.03, n = 12; papilla, 0.63 +/- 0.04, n = 12; tubules, 0.74 +/- 0.04, n = 28; glomeruli, 0.59 +/- 0.03, n = 28; and liver, 0.41 +/- 0.02, n = 28. Enzyme activity was maximal at pH 3.0-3.5 and inhibited more than 90% by pepstatin (6.7 micrograms/ml), suggesting that the enzyme is cathepsin D. In subsequent experiments we measured cathepsin D-like activity in cortex, tubules and glomeruli isolated from rats with puromycin aminonucleoside (PAN)-induced nephrotic syndrome. Treated animals (15 mg of PAN/100g body wt., intraperitoneally) developed proteinuria beginning 4 days after injection and exceeding 900 mg/24h on day 9. In two separate experiments involving 52 animals we observed a significant increase in cathepsin D-like activity in cortex (+82.7%), tubules (+109.6%) and glomeruli (+54.7%) isolated from PAN-treated rats killed during marked proteinuria (day 9, mean total urinary protein excretion: 937 +/- 94 mg/24h). This increase was observed whether the activity was expressed per mg of DNA or per mg of protein. Increased cathepsin D-like activity was first observed in cortex and tubules coincident with the onset of proteinurea (day 4, mean total urinary protein excretion: 112 +/- 23 mg/24h). In contrast with the significant elevation of renal cathepsin D-like activity, the activity (nmol/h per mg of protein) of alpha-L-fucosidase (EC 3.2.1.51), a non-proteolytic enzyme, was markedly decreased in the identical samples used for the measurement of cathepsin D-like activity: cortex (-46.4%); tubules (-46.1%); and glomeruli (-38.5%). In addition to changes in renal enzyme activities, PAN-treated rats excreted large amounts of cathepsin D-like activity in their urine (beginning on day 3) compared with nearly undetectable cathepsin D-like activity in the urine from control rats. The significant increases in glomerular and tubular cathepsin D activity may reflect an important role for this enzyme in the pathophysiology associated with PAN-induced nephrotic syndrome.
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PMID:Increased cathepsin D-like activity in cortex, tubules, and glomeruli isolated from rats with experimental nephrotic syndrome. 649 55

The enzymatic characterization and analytical fractionation of L1210 cells have been performed in view of studying the cellular pharmacology of antitumoral drugs. Several enzymatic activities were detected and their assay conditions optimized. After a gentle homogenization to preserve as much as possible the integrity of the nucleus and cytoplasmic organelles, homogenates were fractionated by differential and isopycnic centrifugation. On the basis of pH dependency, effect of detergents and distributions after cell fractionation, enzymatic activities and biochemical constituents can be classified in several groups and by analogy to other organs or cultured cells, attributed to distinct cellular components. N-Acetyl-beta-glucosaminidase, alpha-L-fucosidase, alpha-D-mannosidase detected at acid pH and cathepsin D are therefore proposed as markers of lysosomes; inosine diphosphatase and uridine monophosphatase as markers of the plasma membrane, while phosphoglucomutase and neutral pyrophosphatase on one hand and galactosyl transferase and alpha-D-mannosidase at pH 6.0 on the other hand are attributed respectively to the cytosol and the Golgi apparatus.
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PMID:Enzymatic characterization and analytical fractionation of L1210 cells. 723 41

Alterations in the activities of certain lysosomal enzymes such as beta-D-galactosidase, beta-D-glucosidase, beta-D-glucuronidase, alpha-L-fucosidase, N-acetyl-beta-D-glucosaminidase, cathepsins B and D were studied in serum and tissue homogenates of buccal mucosa of hamsters treated with 0.5%, 7,12-dimethylbenz[a]anthracene (DMBA) in liquid paraffin. Among the enzymes studied, the activities of beta-D-galactosidase and N-acetyl-beta-D-glucosaminidase showed significant elevation both in serum and tissue homogenates fro papilloma onwards and the elevations were progressive with the development of carcinomas. The elevations in the activities of alpha-D-fucosidase and cathepsin D were found to be significant from papillomatous tissue onwards whereas in serum they showed higher activities only in carcinoma stages. The activities of beta-D-glucosidase, beta-D-glucuronidase and cathepsin B in both serum and in tissue homogenate were elevated markedly only in carcinoma stages. It is suggested that beta-D-galactosidase and N-acetyl-beta-D-glucosaminidase may be used as diagnostic markers for premalignant and malignant lesions of oral mucosa.
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PMID:Studies of the activities of lysosomal enzymes in serum and buccal pouch tissue of hamsters during 7,12-dimethylbenz[a]anthracene-induced carcinogenesis. 862 88

We evaluated the relationships between proteins in cauda epididymis fluid (CEF) and fertility scores of dairy bulls. Fertility was expressed as the percentage point deviation (PD) of bull nonreturn rate from the average fertility of all bulls at an artificial insemination center. The number of services for each bull ranged from 1074 to 52 820, and PD values ranged from +7.7% to -6.6%. CEF from 20 bulls was obtained from vasa deferentia cannulae and was separated from sperm by centrifugation immediately after collection. Samples were evaluated by 2-dimensional (2-D) sodium dodecyl sulfate polyacrylamide gel electrophoresis gels stained with Coomassie blue, and polypeptide maps were analyzed by PDQuest software. Protein quantities, defined as the total integrated optical density of the spots, were compared between groups of high-fertility sires (n = 12; PD >or= 0) and low-fertility sires (n = 8; PD < 0) and were also used as independent variables in regression analysis. Proteins were identified by capillary liquid chromatography-nanoelectrospray ionization-tandem mass spectrometry. An average of 118 spots was detected in 2-D maps of the CEF, but we were unable to distinguish any protein that was expressed only in high-fertility or in low-fertility bulls. However, the amount of alpha-L-fucosidase 2 and cathepsin D was 2.3- and 2.4-fold greater (P < .05) in high-fertility than in low-fertility bulls, respectively. Conversely, the intensities of 3 isoforms (24-27 kd; pl 6.3-5.8) of prostaglandin D-synthase (PGDS) were from 3.2- to 2.2-fold greater in low-fertility sires (P < .05). An empirical regression model established that a significant proportion (R(2) = 0.72; P < .0001) of the variation in fertility scores (PD values) was explained by the intensities of cathepsin D and 1 isoform of PGDS (24 kd; pl 6.3). Thus, multiple proteins present in the CEF are potential biomarkers of fertility in high-use, mature Holstein bulls.
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PMID:Proteins of the cauda epididymal fluid associated with fertility of mature dairy bulls. 1658 9