Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In some patients with genetic forms of extreme insulin resistance, there is a marked decrease in the number of insulin receptors on the cell surface. We studied an insulin-resistant patient (RM-1) with the Rabson-Mendenhall syndrome. As judged by insulin-binding studies, Epstein-Barr virus-transformed lymphocytes from patient RM-1 exhibit a 90% decrease in the number of insulin receptors. Similarly, with either lactoperoxidase-catalyzed radioiodination of cell surface receptors or biosynthetic labeling of receptors with [3H]glucosamine, we demonstrated an 80-90% decrease in the number of insulin receptors in cells from patient RM-1. Previous studies have shown that the marked decrease in insulin receptors of the Rabson-Mendenhall patient is not due to accelerated receptor degradation. Therefore, we investigated the possibility that a slow rate of receptor biosynthesis might account for the 90% reduction of insulin receptors in cells from this patient. Insulin-receptor biosynthesis proceeds through a glycoprotein precursor with an apparent Mr of 190,000. It undergoes endopeptidase cleavage and further posttranslational processing to yield the mature 135,000- and 95,000-Mr glycoprotein subunits. We studied the biosynthesis of the 190,000-Mr precursor and mature receptor subunits by a pulse-chase labeling technique with [2-3H]mannose. The time course of insulin-receptor biosynthesis appeared normal in cells from patient RM-1, despite a 10-fold reduction in the number of receptors on the cell surface. Parallel pulse-chase experiments with either [2-3H]mannose or [35S]methionine yielded the same results regardless of which label was employed. Thus, the receptor precursor in the Rabson-Mendenhall patient seems to be synthesized at a normal rat.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Insulin-receptor biosynthesis in cultured lymphocytes from an insulin-resistant patient (Rabson-Mendenhall syndrome). Evidence for defect before insertion of receptor into plasma membrane. 372 Oct 65

One way in which serum promotes survival of primary cultured hepatocytes is by inhibiting plasma membrane protease (Nakamura, T., Asami, O., Tanaka, K., and Ichihara, A. (1984) Exp. Cell Res. 155, 81-91). One of these proteases was solubilized from the plasma membranes of rat liver with 4% octyl glucoside and purified to a homogeneous state by affinity chromatography on bovine pancreatic trypsin inhibitor linked to Sepharose 4B. The protease had an apparent Mr = 120,000 by Sephacryl S-200 gel filtration and the Mr of its subunits was 30,000, as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. It appeared to be a glycoprotein. A high concentration of detergent was necessary to keep the protein soluble. The purified enzyme readily hydrolyzed synthetic tripeptide nitroanilides at sites adjacent to Arg or Lys residues, but did not degrade synthetic substrates of chymotrypsin, elastase, or aminopeptidase. It showed endopeptidase activity, hydrolyzing various proteins such as casein, hemoglobin, and denatured albumin. The enzyme was strongly inhibited by diisopropyl fluorophosphate, phenylmethanesulfonyl fluoride, bovine pancreatic trypsin inhibitor, leupeptin, antipain, and alpha 1-antitrypsin, but not by chymostatin, elastatinal, or inhibitors of carboxyl, thiol, or metallo proteases, suggesting that it is a seryl trypsin-like protease. This protease was found in plasma membranes of rat and mouse liver and in small amounts in those of kidney, but not in those of brain, red cells, Ehrlich ascites tumor, or two Morris hepatomas, suggesting that it may be involved in differentiated functions of normal hepatocytes.
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PMID:A unique trypsin-like protease associated with plasma membranes of rat liver. 394 38

A clonogenic assay has been developed that utilizes Burkitt's lymphoma tumor cell lines to detect elimination of up to 5 logs of tumor cell contamination within human bone marrow. Different Burkitt's lymphoma lines bear one or more of a group of markers, including common acute lymphoblastic leukemia antigen gp26 (glycoprotein with a molecular weight of 26,000), B1, surface membrane immunoglobulin, HLA, beta 2-microglobulin, and Ia. Burkitt's tumor cells of the Namalwa line have been mixed with a 20-fold excess of irradiated human bone marrow cells. After treatment with one or more monoclonal antibodies and rabbit complement (RC), mixtures have been grown on a monolayer of irradiated human bone marrow cells and tumor cells enumerated by limiting dilution. Multiple treatments with antibody and RC were more effective than a single treatment in destroying clonogenic tumor cells which bore relevant determinants. Human serum components inhibited the lytic activity of RC in the presence of murine monoclonal antibodies. The total concentration of bone marrow cells proved critical in determining the complete elimination of tumor. Incubation of the Namalwa tumor cell line with RC and the J2 anti-gp26 eliminated more than 3 logs of malignant cells from a 20-fold excess of human bone marrow. Combinations of two monoclonal antibodies were more effective than any single antibody in eliminating Namalwa cells. A combination of three monoclonal reagents was no more effective than a combination of J2 and B1 or J2 and J5 in eliminating Namalwa cells. Treatment of human bone marrow with three antibodies and RC did not, however, produce a selective loss of nonmalignant GM-CFU-C, CFU-E, or BFU-E.
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PMID:Elimination of malignant clonogenic cells from human bone marrow using multiple monoclonal antibodies and complement. 396 24

1. Some properties of a brush-border neutral endopeptidase purified from rabbit kidney were investigated. The peptidase was assayed by its ability to hydrolyse [(125)I]iodoinsulin B chain. 2. The enzyme was found to be homogeneous when studied in the analytical ultracentrifuge and stained as a single glycoprotein band after electrophoresis in polyacrylamide gels. 3. The molecular weight was estimated by gel filtration in columns of Sephadex G-200, by polyacrylamide-gel electrophoresis in the presence of 2-mercapto-ethanol and sodium dodecyl sulphate and by sedimentation equilibrium in the ultra-centrifuge. The estimates fell within the range 87000-96000. The mean from two sedimentation equilibrium experiments was 93000, though this estimate may be slightly inflated because of the carbohydrate component of the enzyme. No evidence of dissociation into smaller subunits was obtained in the presence of thiol, sodium dodecyl sulphate or guanidine hydrochloride. 4. The endopeptidase was maximally active at pH6.0, although in phosphate buffer, which was strongly inhibitory, an optimum above pH8 was observed. 5. The enzyme was not affected by di-isopropyl phosphofluoridate nor by several thiol reagents. It was, however, strongly inhibited by many thiols and by EDTA and other chelating agents. 6. Although activity of the EDTA-treated enzyme could be partially restored by various bivalent metal ions, the optimum concentration for its reactivation by Zn(2+) was lower than that for other ions. This metal was detected in the enzyme preparation by atomic absorption spectrophotometry in an amount equivalent to approximately one atom/mol. 7. The enzyme is the only endopeptidase shown to be located in the kidney brush border and is the first mammalian example of a neutral Zn(2+)- activated endopeptidase to be characterized.
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PMID:The molecular weight and properties of a neutral metallo-endopeptidase from rabbit kidney brush border. 421 6

CALLA is a 100,000-dalton surface glycoprotein expressed by malignant cells of patients with clinically important subtypes of acute leukemia. Incubation of human leukemic cells expressing CALLA with specific monoclonal antibody (J5) at 37 degrees C causes rapid and selective internalization and degradation of this antigen (antigenic modulation). In these studies we show that CALLA-specific monoclonal antibodies also identify a cell surface glycoprotein having a m. w. of approximately 100,000 on 2 to 6% of nonmyeloid nucleated cells of normal adult bone marrow, on normal fibroblasts in tissue culture, and on cells of several nonhematopoietic human tumor cell lines. J5 antibody similarly modulates the surface expression of CALLA on nonleukemic cell populations, although the extent of modulation at a given concentration of antibody varied considerably. Modulation was almost complete for CALLA on cells of normal bone marrow, but was highly variable for cells of nonhematopoietic cell lines, possibly reflecting variability in antibody access to surface antigen. Using fluoresceinated or iodinated J5 antibody to modulate expression of CALLA on cells of leukemic cell lines, we show that antibody-antigen complexes undergo a temperature-dependent redistribution on the cell surface during modulation to form microaggregates. Antibody as well as antigen is then internalized. Studies of [35S]methionine-labeled cells indicate that synthesis of CALLA continues despite modulation of its surface expression by specific antibody, implying that the presence of CALLA on the cell surface reflects a dynamic equilibrium between the processes of surface expression of newly synthesized glycoprotein and its spontaneous and antibody-mediated clearance. The implications of these observations for immunotherapy are discussed.
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PMID:Distribution and modulation of a human leukemia-associated antigen (CALLA). 622 2

Intraperitoneal administration of leupeptin to rats induced a hemoglobin-hydrolyzing protease which was most active at pH 3.5 and was insensitive to pepstatin in various tissues such as the liver, kidney, and muscle, as observed previously in adult rat hepatocytes in primary culture (Tanaka, K., Ikegaki, N., and Ichihara, A. (1979) Biochem. Biophys. Res. Commun. 91, 102-107). The induced acidic protease was purified about 600-fold in 30% yield from rat liver by conventional chromatographic techniques. The purified enzyme appeared homogeneous by polyacrylamide gel electrophoresis in the presence or absence of sodium dodecyl sulfate and was a monomeric protein of Mr = 20,000. The enzyme appeared to be a glycoprotein because its induction was blocked by the addition of tunicamycin to cultures of hepatocytes and because the induced protease was absorbed on concanavalin A-Sepharose and eluted with methylglucoside. It seemed to be present in lysosomes and was fairly stable at various pH values and temperatures. It showed endopeptidase activity on various protein substrates, but scarcely hydrolyzed N-substituted derivatives of arginine. It did not hydrolyze esters, showed no aminopeptidase or carboxypeptidase activity, and did not inactivate glucose-6-phosphate dehydrogenase or aldolase. The enzyme appeared to be a thiol protease, since it was strongly inhibited by sulfhydryl-reactive compounds and N-( [N-(1-3-trans-carboxyoxiran-2-carbonyl)-L-leucyl]-agmatine and was not inhibited by reagents specific for carboxyl-, serine-, or metalloproteases. This induced protease could be separated from cathepsins B, D, and H by chromatography. The enzyme was similar to cathepsin L in chromatographic behavior, Mr and pI, but differed from the latter in stability and in its inability to inactivate some enzymes. These results suggest that it differs from any known proteases found previously in rat liver.
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PMID:Purification and characterization of hemoglobin-hydrolyzing acidic thiol protease induced by leupeptin in rat liver. 637 Oct 12

Succinyl-trialanine paranitroanilide, a specific synthetic substrate of elastases, was shown to be hydrolyzed by Triton X-100 extracts of human skin fibroblasts at near neutral pH. The neutral endopeptidase has been partially purified by ion exchange chromatography (DEAE Sephadex) and affinity chromatography using an AH-Sepharose (Ala)3 column. The enzyme has been purified 85-fold and appears to be a metalloprotease as shown by its inhibitory profile. In its partially purified form, the neutral endopeptidase was found inactive toward benzoyl arginine paranitroanilide, benzoyl tyrosine paranitroanilide, azocasein, type I collagen, and [3H]ligamentum nuchae-insoluble elastin. Structural glycoprotein microfibrils isolated from porcine aorta are extensively degraded by this neutral protease. It could also hydrolyze, but to a lesser extent, insoluble elastin purified from human aortas; it was, however, found inactive toward bovine ligamentum nuchae elastin. Its potentiality to degrade the human skin elastic fiber system (namely elastic fibers, oxytalan, and elaunin fibers) has been assessed by a morphometric analysis of the length of these fibers (on tissue sections appropriately stained to identify the components of the elastic fiber system) prior to and after enzyme action. Analysis of the data obtained by morphometry indicated that this neutral protease attacked rapidly both elaunin and oxytalan fibers of human dermis, but only slowly the mature elastic fibers.
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PMID:On the presence of a metalloprotease in human skin fibroblasts that degrades the human skin elastic fiber system. 638 8

Meprin, a glycoprotein with potent metalloendopeptidase activity, is an integral component of the brush border membrane of mouse kidney. Previously we reported that genealogically related inbred mouse strains (C3H and CBA) are markedly deficient in the activity of this enzyme. We report here that meprin deficiency is inherited as an autosomal recessive trait and that several other inbred strains also express low levels of meprin activity. All of the inbred strains deficient in meprin activity are of the H-2k haplotype; however, two strains of this haplotype (C58 and C57BR/cd) expressed normal levels of the proteinase. Congeneic and recombinant mouse strains were examined to determine whether the deficiency was linked to the H-2 complex. The gene controlling the activity of meprin (Mep-1) maps on chromosome 17 to the right of the D end of the major histocompatibility complex. The Mep-1 gene is closely linked to a gene that controls isoenzyme patterns of phosphoglycerate kinase (Pgk-2). This work represents the localization of a gene that determines the activity of an integral cellular endopeptidase in mammalian tissues. In addition, the Mep-1 gene is the only identified gene linked to the major histocompatibility complex that regulates a proteinase activity.
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PMID:Mep-1 gene controlling a kidney metalloendopeptidase is linked to the major histocompatibility complex in mice. 638 65

"Enkephalinase," a membrane-bound peptidase hydrolyzing the Gly3-Phe4 amide bond of enkephalins, initially characterized in brain, was purified from a rat kidney microsomal fraction. After differential solubilization with Triton X-100, the use of DEAE-Sephadex, concanavalin A, and hydroxylapatite chromatography led to a 2000-fold purification, close to homogeneity. Renal enkephalinase appears to be a glycoprotein Mr = 92,000-95,000 with catalytic properties and sensitivity to chelating agents and inhibitors (Thiorphan, phosphoramidon) very similar to those of the cerebral enzyme. The enzyme co-purified until the final step with "renal brush-border neutral proteinase" (EC 3.4.24.11) activity assayed with 125I-insulin B chain as substrate and displaying similar sensitivity to inhibitors. The specificity of the purified enkephalinase has been studied using either peptides derived from the enkephalins or model peptides of general formula (Ala)m-Tyr-(Ala)n as substrates. In all cases the bond cleaved was that involving the amino group of an aromatic residue, specificity being also defined by the nature of the neighboring residue on the COOH-terminal side. A free carboxyl in the latter residue was essential in the two series of substrates, indicating that enkephalinase more efficiently functions as a dipeptidyl carboxypeptidase than as an endopeptidase.
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PMID:Enkephalinase from rat kidney. Purification, characterization, and study of substrate specificity. 638 47

Four distinct rat monoclonal antibodies against the common ALL antigen (CALLA, gp 100) were obtained in a single fusion. Rat AL2, AL3, AL4, AL5 and the previously reported mouse J5 monoclonal antibodies identified the same subsets of leukaemic cells. AL2 and AL3 reacted weakly with terminal transferase-positive cells in normal bone marrow and foetal liver, as well as with a minority of mature granulocytes in blood. Immunoprecipitation experiments and competitive binding assays demonstrated that the four rat antibodies and J5 bound to the same glycoprotein of approximately 100,000 mol. wt. This set of rat monoclonal antibodies directed against CALLA has not only a diagnostic usefulness but may also be of therapeutic value.
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PMID:Rat AL2, AL3, AL4 and AL5 monoclonal antibodies bind to the common acute lymphoblastic leukaemia antigen (CALLA gp 100). 657 89


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