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:3.4.21.1 (chymotrypsin)
10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Proteolytic removal of the pre-segment from growing nascent chains of pre-human placental lactogen (hPL) occurred during in vitro translation of placental mRNA if crude membranes derived from ascites lysates, dog pancreas, or rat liver rough endoplasmic reticulum were added to the translation mixtures. The cotranslational proteolytic event was inhibited by the peptide protease inhibitor, chymostatin, but not by leupeptin, antipain, or elastatinal. The proteases involved in cleavage were solubilized with detergent and converted completed pre-hPL to hPL (post-translational processing). Direct assay of the solubilized membranes, with synthetic fluorogenic aminocoumarin peptide substrates, revealed no significant tryptic or elastase-like activity, but activity against a chymotrypsin substrate [(succinyl-Ala-Ala-Phe)-7-amino-4-methyl-coumarin] was found. This activity was dependent upon both an endopeptidase and an aminopeptidase. Although bestatin inhibited the aminopeptidase activity, it had no effect on the endopeptidase or on post-translational cleavage. Although this endopeptidase cleaved on the COOH side of an alanine residue, it was not inhibited by elastatinal. However, it was inhibited by high levels of chymostatin and by some serine protease inhibitors.
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PMID:Characterization of an endopeptidase involved in pre-protein processing. 29 60

Distributions of parathyroid hormone (PTH), proparathyroid hormone (ProPTH), preproparathyroid hormone (PreProPTH), and parathyroid secretory protein (PSP) were analyzed in subcellular fractions prepared from homogenates of bovine parathyroid glands. Slices of bovine parathyroid glands were incubated with radiolabeled amino acids for 3--30 min to selectively label newly synthesized proteins. Subcellular fractions were prepared from homogenates of the gland slices by differential centrifugation. Newly synthesized labeled hormonal polypeptides in the fractions were analyzed by electrophoresis on polyacrylamide gels, and total amounts of PTH and ProPTH (previously formed and newly synthesized) were determined by immunoassay. Ninety percent of total immunoreactive, 70--80% of newly synthesized PTH, ProPTH, and PreProPTH, and 50% of PSP were found in sedimentable particulate fractions. The low speed (800 X g) pellet, which consisted predominantly of cell debris and nuclei with adherent remnants of cytoplasm, contained 30--50% of the ProPTH and PTH. The intermediate speed (10,000 X g) pellet, which contained granules, was relatively enriched in PTH. Most particulate-associated hormone could be solubilized by treatment with deoxycholate (DOC) 98% and 97% of radiolabeled and 93% and 83% of immunoreactive ProPTH and PTH, respectively, in particulates sedimenting at 10,000 and 105,000 X g were rendered DOC-soluble. Approximately 50% of the PTH and ProPTH in the particulates resisted digestion by combined trypsin and chymotrypsin, whereas PreProPTH was completely susceptible to proteolysis. Up to 50% of the radiolabeled PTH and ProPTH added exogenously to parathyroid gland slices before homogenization became associated with the particulate fractions, and 70--80% or radiolabeled PreProPTH added to the subcellular fractions readily associated with the sedimentable material. The results indicate that in homogenates of parathyroid glands, PTH, ProPTH, PreProPTH, and PSP are associated with particulate structures. Furthermore, up to 50% of the association of ProPTH, PTH, and PSP with particulate fractions seems to be nonsepcific and occurs during the disruption of the tissues. The remaining 50% or more of hormonal protein is presumably sequestered within membrane-limited structures, such as microsomal vesicles. The complete susceptibility in particulate fractions of newly synthesized PreProPTH, but not of ProPTH, to limited proteolysis indicates that the two precursors are located in different subcellular compartments and suggests that PreProPTH is converted to ProPTH before its entry into the intracisternal space of the endoplasmic reticulum. Alternatively, the PreProPTH identified in parathyroid gland slices may represent polypeptide chains synthesized in the cell sol on polyribosomes that are not attached to endoplasmic reticulum but are adsorbed nonspecifically to the particulate fraction of the cell during the process of tissue homogenization.
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PMID:Subcellular distributions of parathyroid hormone, hormonal precursors, and parathyroid secretory protein. 44 53

Hydrolysis of the membrane proteins and phospholipid headgroups of rat liver rough endoplasmic reticulum membranes showed that the ribosomal binding sites involve membrane proteins susceptible to low concentrations of trypsin, chymotrypsin, and papain. Three membrane proteins having molecular weights of 120 000, 93 000 and 36 000 are found to be altered by trypsin and chymotrypsin treatment. Also the polar headgroup of phosphatidylinositol appears to play a role in the binding process.
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PMID:The role of membrane proteins and phospholipids in the interaction of ribosomes with endoplasmic reticulum membranes. 118 90

Light microscopic observations using Nomarski optics on the aldehyde-fixed hypothalamus of normal adult cats, monkeys and rabbits revealed the presence of cells in the supraoptic, paraventricular and periventricular nuclei which possessed yellow birefringent inclusions. Immunogold labelling showed that in each species the cells displayed oxytocin-like immunoreactivity, both in electron-dense inclusions within some (but not all) cisterns of rough endoplasmic reticulum and in secretory granules. The cells in cats and rabbits were in all respects indistinguishable from the homologous 'birefringent' cells previously described in rats, but in monkeys, cells frequently contained additional inclusions in cisterns of rough endoplasmic reticulum which did not display oxytocin or vasopressin-like immunoreactivity, even after trypsin, pepsin or chymotrypsin treatment of sections. Observations on cats and rabbits using fluorescence microscopy revealed that the birefringent cells possessed bright autofluorescence which facilitated the identification of more cells than were seen using Nomarski optics alone. Autofluorescence was abolished when sections were mounted in glycerol, or when exposed to light for protracted periods of time. Attempts to label for monoamines in these cells were not successful, suggesting that the fluorescence is not due to aldehyde-induced amine fluorescence. It is not clear why neuropeptides are retained in some rough endoplasmic reticulum cisterns. It is possible that these birefringent cells contain a peptide, or peptides, which are abnormal in some manner, or which may be other members of the oxytocin gene family. Alternatively, the processing of neuropeptides to permit their export to the Golgi apparatus may be deficient. Acetylcholinesterase (AChE) histochemistry revealed that, unlike other oxytocin neurons, cells with intracellular accretions lacked detectable acetyl cholinesterase. As AChE is a known peptidase, it may be involved in regulating peptide export from the rough endoplasmic reticulum.
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PMID:Neuropeptide accretions in the endoplasmic reticulum of oxytocinergic neurons in cats, monkeys and rabbits: a widespread phenomenon. 129 66

Tumor cells and urine-voided cells from patients with invasive bladder carcinoma as well as from healthy patients were examined cytologically, ultrastructurally and immunocytochemically. The ultrastructure of tumor cells showed an abundant, dilated, rough endoplasmic reticulum in the form of membrane-bound vacuoles full of granular to fibrillar material located perinuclearly and/or paranuclearly. Some cells exhibited enlarged modified lysosomes containing sparce flocculent and particulate precipitate. Papanicolaou staining of these cells showed two basophilic cytoplasmic textures, one green glossy-patchy, perinuclearly and/or paranuclearly, well segregated from the other texture of peripheral hematoxylinophilic foamy cytoplasm, comparable to the cytologic features of cell cultures originating in invasive bladder carcinoma. PAS diastase showed double distribution and texture of the perinuclear glycosaminoglycans, a glossy accumulated mass and large granules. Glycosaminoglycan sacs similar to those of cell cultures were also present in tumor-dispersed cells. There was a nonspecific binding of antisera against lysozyme, human chorionic gonadotropin and alpha 1-trypsin in normal and tumor cells. Tumor cells and tissues were positive for alpha 1-chymotrypsin distributed perinuclearly and in large spheres. Normal cells lacked the above characteristics. The results indicate that it is feasible to use the aforementioned characteristics in conjunction with the existing bladder-cytologic criteria for malignancy as markers in urothelial cancer with regard to prognosis of superficial tumors with high malignant potential.
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PMID:A cytologic, ultrastructural and immunocytochemical comparison of tumor cells and cell cultures originating in invasive bladder carcinoma. 137 23

We have examined the microscopic appearance, immunohistochemical staining properties, and clinical behavior of 28 cases of acinar cell carcinoma of the pancreas. Two of the tumors occurred in children. The adult patients ranged in age from 40 to 81 years (mean, 62 years). Males greatly outnumbered females, and most of the patients were white. Presenting symptoms were nonspecific, and jaundice was infrequent. The frequently reported complications from increased serum lipase levels (i.e., arthralgias and subcutaneous fat necrosis) were present in only 16% of the patients. Grossly, the tumors were relatively circumscribed and fleshy, averaging 10.8 cm, with occasionally extensive hemorrhage and necrosis. Microscopically, the tumors were very cellular and characteristically lacked a desmoplastic stroma. Acinar, solid, trabecular, and glandular patterns of growth were identified; individual tumors were usually mixed. Nuclei were round to oval, with minimal pleomorphism and single prominent nucleoli. Mitotic activity was variable. In general the cytoplasm was moderately abundant, eosinophilic, and granular, but many of the solid tumors had cells with scanty cytoplasm. Characteristic periodic acid-Schiff-positive, diastase-resistant cytoplasmic granules were demonstrated in greater than 90% of the cases, and the butyrate esterase histochemical stain for lipase activity was positive in 73%. Immunohistochemically, there was positivity for trypsin in 100% of the cases, for lipase in 77%, for chymotrypsin in 38%, and for amylase in 31%. A minor endocrine component was recognized with antibodies against chromogranin or islet cell hormones in 42% of the tumors. Ultrastructurally, exocrine secretory features were present, with polarized cells showing microvillilined lumina, abundant rough endoplasmic reticulum, and 125-1,000-nm zymogen-like granules. In addition, many cases showed pleomorphic electron-dense granules measuring up to 3,500 nm and containing fibrillary internal structures. Follow-up information was available in 88% of the cases. Half of the patients had metastatic disease at presentation and an additional 23% subsequently developed metastases, which were usually restricted to the regional lymph nodes and liver. The mean survival for all cases was 18 months, with 1- and 3-year survivals of 57 and 26%, respectively. Patients presenting before age 60 years survived nearly twice as long as older patients did. Stage also influenced prognosis, whereas the histologic subtype of the tumors and the location within the pancreas correlated only weakly with survival.
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PMID:Acinar cell carcinoma of the pancreas. A clinicopathologic study of 28 cases. 138 74

When the effect of MY-1250 (5,6-dihydro-7,8-dimethyl-4,5-dioxo-4 H-pyrano [3,2-c] quinoline-2-carboxylic acid) on histamine release from rat peritoneal mast cells induced by compound 48/80 was studied, MY-1250 caused a significant inhibition of histamine release at concentrations higher than 3 microM. Furthermore, the compound inhibited not only 45C a uptake into the mast cells but also Ca2+ release from the intracellular Ca store at a concentration of 10 microM in both cases. By contrast, MY-1250 did not affect either histamine release from permeabilized mast cells induced by TPA, IP3 and GTP gamma S or Ca2+ release from the endoplasmic reticulum induced by IP3. In the chopped lung preparations, MY-1250 at doses of 10 and 100 microM caused a significant inhibition in histamine release from the pieces of actively sensitized guinea pigs exposed to antigen and simultaneously prevented a decrease in intracellular cAMP contents taking place in association with antigen-antibody reaction. No significant changes were effected by MY-1250 in alpha-chymotrypsin activity and phospholipase A2 activity. Also, no antagonistic effects on LTD4 and PAF were observed.
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PMID:Inhibitory effect of MY-1250 on histamine release from rat peritoneal mast cells and guinea pig lung fragments: the elucidation of the mechanism. 171 61

The spike protein of Semliki Forest virus is composed of three subunits, E1, E2, and E3, which mediate the fusion of the virus membrane with that of the host cell. E2 and E3 are synthesized as a precursor, p62, which is cleaved post-translationally after an Arg-His-Arg-Arg sequence. In vitro mutagenesis of a cDNA clone of the spike proteins was used to specifically alter amino acids in this cleavage site. Cleavage of p62 was completely blocked by mutation of the proximal Arg residue to Phe, without affecting transport or surface expression of the spike protein. The cleavage mutation resulted in the loss of spike protein fusion activity within the physiological pH range. Fusion activity was restored by cleavage with exogenous chymotrypsin and showed the same low pH dependence as that of wild type. The cleavage sensitivity of newly synthesized p62 was investigated by pulse-chase analysis and chymotrypsin treatment in detergent solution. p62 was sensitive to cleavage immediately following its synthesis. Protein trapped in the rough endoplasmic reticulum or Golgi apparatus by carbonyl cyanide m-chlorophenylhydrazone, monensin, or Brefeldin A treatment was also fully sensitive to cleavage. These results suggest that p62 does not require an organelle-mediated conformational change for processing. Thus, in vivo, the site of p62 processing is probably controlled by the location or activity of the cleavage enzyme, rather than the sensitivity of the p62 substrate.
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PMID:Processing of the p62 envelope precursor protein of Semliki Forest virus. 200 12

Activity of a chymotrypsin-type serine protease was found in a subline of rat basophilic leukemia (RBL-2H3) cells. The protease was immunologically cross-reactive with anti-atypical mast cell protease immunoglobulin (Ig) G, and its activity was inhibited in a dose-dependent manner by the antibody. The apparent m.w. of the protease that reacted with the antibody was 25,000, which was identical with that of atypical mast cell protease in rat mucosal mast cells. These results show that the chymotrypsin type serine protease in RBL-2H3 cells is immunologically identical with atypical mast cell protease, which was first purified from rat small intestine. Immunohistochemical studies showed that the protease was located not only in intracytoplasmic granules but also in organelles synthesizing protein, such as cisternae of the rough endoplasmic reticulum, perinuclear spaces, and the Golgi apparatus. However, no immunoreactivity was demonstrated in rat basophils. The activity of the protease increased in the exponential phase of growth of RBL-2H3 cells in which some activity was also detected in the medium, and it decreased in the late stationary phase.
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PMID:A chymotrypsin-type serine protease in rat basophilic leukemia cells: evidence for its immunologic identity with atypical mast cell protease. 241 25

Prostaglandin H synthase catalyzes the first step in the conversion of polyunsaturated fatty acids to prostaglandins, thromboxanes, and prostacyclins. The enzyme is normally bound to the endoplasmic reticulum membrane, but can be purified to homogeneity after solubilization with detergent. The topologies of the microsomal and the pure detergent-solubilized forms of the synthase were compared by an examination of their sensitivity to degradation by proteases, of the effect of heme on this protease sensitivity, and of the sizes of proteolytic fragments produced. For the microsomal synthase, the localization of proteolytic fragments was also determined. Analysis of the microsomal proteins after proteolytic digests involved separation by polyacrylamide gel electrophoresis and selective detection of the synthase-derived polypeptides with a polyclonal antibody against the pure synthase. With both the microsomal and the pure synthase, incubation with trypsin led to a progressive loss of cyclooxygenase activity and cleavage of the synthase subunit (70K Da) into two fragments of 38K and 33K Da. Incubation of the detergent-solubilized form of the synthase with proteinase K and chymotrypsin also produced a very similar pair of fragments (38K and 33K Da). After incubation of the microsomes with trypsin both the 38K and 33K Da fragments from the synthase remained bound to the membrane; no cyclooxygenase activity was released in soluble form from the microsomes by trypsin. Further, neither trypsin nor proteinase K released soluble radiolabeled peptides from microsomes whose synthase had been labeled with [acetyl-14C]-aspirin. With the microsomal synthase the sensitivity to protease (66% of the cyclooxygenase activity was lost after 90 min incubation with proteinase K) was enhanced by depletion of heme (84% of activity lost) and was decreased by addition of heme (only 20% of activity lost), just as had been previously demonstrated for the detergent-solubilized synthase. At each of several intervals during an incubation of the pure synthase with trypsin the extent of cleavage of the synthase polypeptide correlated reasonably well with the extent of loss of cyclooxygenase activity; a similar relation between proteolytic cleavage and loss of activity was observed in digests of the pure synthase supplemented with differing amounts of heme.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Topographic studies of microsomal and pure prostaglandin H synthase. 249 19


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