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:3.4.24.3 (collagenase)
18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transformation of the chick fibroblast surface has been studied in cells infected with Schmidt-Ruppin Rous sarcoma virus and the temperature-sensitive mutant of this virus, TS-68. Major findings following transformation induced by a shift from nonpermissive (41 C.) to permissive (36 C.) temperature in TS-68 infected cells were: (1) rapid cessation or slowing of the synthesis of a protein, M.W. 100-200,000, localization uncertain; (2) cessation or slowing of the synthesis of a plasma membrane protein, M.W. 45,000, within 2-4 hours; (3) cessation or slowing of the synthesis of a large trypsin- and collagenase- sensitive protein (M.W. greater than 200,000) only after an extended period of morphologic transformation. In addition, increased quantities of type-specific viral antigen in the membranes of infected cells were observed in TS-68-infected cells at 41 compared with 36 C.
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PMID:Comparisons of major cell-surface proteins of normal and transformed cells. 16 7

The 16S and 8S forms of acetylcholinesterase (AchE), which are composed of an elongated tail structure in addition to the more globular catalytic subunits, were extracted and purified from membranes from Torpedo californica electric organs. Their subunit compositions and quaternary structures were compared with 11S lytic enzyme which is derived from collagenase or trypsin treatment of the membranes and devoid of the tail unit. Upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the absence of reducing agent, appreciable populations of monomeric through tetrameric species are observed for the 11S form. Under the same conditions, the 16S form yields only monomer and dimer in addition to a higher molecular weight species. If complete reduction is effected, only the 80,000 molecular weight monomer is dominant for both the 11S and 16S forms. Cross-linking of the 11S form by dimethyl suberimidate followed by reduction yields monomer through tetramer in descending frequency, while the 16S form again shows a high molecular weight species. A comparison of the composition of the 11S and 16S forms reveals that the latter has an increased glycine content, and 1.1 and 0.3 mol % hydroxyproline and hydroxylysine, respectively. Collagenases that have been purified to homogencity and are devoid of amidase and caseinolytic activity, but active against native collagen, will convert 16S acetylcholinesterase to the 11S form. Thus, composition and substrate behavior of the 16S enzyme are indicative of the tail unit containing a collagen-like sequence. A membrane fraction enriched in acetylcholinesterase and components of basement membrane can be separated from the major portion of the membrane protein. The 16S but not the 11S form reassociates selectively with this membrane fraction. These findings reveal distinct similarities between the tail unit of acetylcholinesterase and basement membrane components and suggest a primary association of AchE with the basement membrane.
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PMID:Molecular forms of acetylcholinesterase from Torpedo californica: their relationship to synaptic membranes. 17 42

The amount of 125I-IgG which bound to membranes isolated from the human placenta was competitively inhibited by the presence of increasing amounts of unlabeled IgG but not by unlabeled albumin. The relationship between membrane-bound and free IgG indicated the presence of membrane receptors with an appreciable affinity for IgG. Incubation of membranes with collagenase or neuraminidase did not results in appreciable reduction of IgG-membrane binding, indicating that neither intact collagen nor sialic acid play an important role in the binding. Placental surface membranes isolated by salt extraction bound 3.79+/- 1.78 (SD) pmol IgG/microgram membrane protein, whereas membranes isolated by differential centrifugation bound only 1.61 +/- 0.24 pmol/microgram (p less than 0.02). The fraction of a preparation of solubilized membranes which bound to an IgG affinity column yielded on polyacrylamide gel electrophoresis three prominent protein bands which had molecular weights of 3.7 X 10(4), 4.5 X 10(4) and 6.0 X 10(4) daltons. These findings are consistent with the existence of a limited number of receptors for IgG on placental membranes, including IgG receptors on the microvillus membrane of the syncytial trophoblast. The latter, in accordance with Brambell's hypothesis, could be of importance in the transplacental transport of maternal IgG.
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PMID:Properties of receptors for IgG on human placental cell membranes. 63 15

Collagen, the major extracellular matrix protein, is also a membrane protein. Two types of collagen are detected on the normal human fibroblast membrane in culture, type I collagen and a new immunologically and chemically distinct collagen, type M (membrane) collagen. Antibodies to type M collagen elicited complement-mediated cytotoxicity, which could be blocked by pretreatment of the cells with bacterial collagenase or the antibody with type M collagen. Pretreatment of the cells with other proteolytic enzymes or the antibody with type I collagen or type III collagen had no effect on this complement-mediated cytotoxicity. Although type I collagen is the major collagen synthesized by normal human fibroblasts type M collagen may be the major cell membrane collagen and may be a major cell membrane component.
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PMID:Immunologic characterization of the membrane-bound collagen in normal human fibroblasts: identification of a distinct membrane collagen. 93 39

Tetracycline resistance in the Enterobacteriaceae is mediated by a number of genetically related, usually plasmid-borne, determinants which specify an efflux system involving an inner membrane protein, Tet. Attempts to overproduce the Tn10 (Class B)-encoded Tet in Escherichia coli by cloning the structural gene tet downstream of the lambda PL promoter under regulation by temperature-sensitive lambda repressor cI857 were unsuccessful; induction at 42 degrees C resulted in filamentous, non-viable cells containing little detectable overproduction of the protein. However, cells containing tet fused to lacZ were resistant to tetracycline at 30 degrees C and synthesized modest amounts of a large fusion protein when induced at 42 degrees C. Fusion of the N-terminal half or the first 38 amino acids of tet to lacZ did lead to increased production of fusion proteins. Fusions could be purified by size or by LacZ immunoaffinity or substrate-affinity chromatography. In the latter method, selected detergents were required to counteract nonspecific binding of Tet to the adsorbant. Amino acid sequencing of the N-terminus of Tet-LacZ fusion proteins indicated that most molecules were blocked at this terminus. The sequence of an unblocked subpopulation was consistent with that expected from the nucleotide sequence. A collagen peptide linker, genetically placed between tet and lacZ, allowed recovery of purified Tet protein after collagenase treatment of the purified fusion protein.
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PMID:Overproduction and purification of the Tn10-specified inner membrane tetracycline resistance protein Tet using fusions to beta-galactosidase. 217 17

The effects of the enzymes collagenase, pepsin, chondroitinase ABC and keratanase on the polypeptide composition of the mammalian tectorial membrane have been analysed using one dimensional SDS-polyacrylamide gel electrophoresis (SDS-PAGE). After reduction at least ten polypeptides can be consistently and clearly recognized in SDS gels with molecular weights relative to globular protein standards of 245, 235, 190, 165, 155, 145, 100, 93, 60-73 and 35-49 kDa. With the exception of the 60-73 and 35-49 kDa bands all these polypeptides are sensitive to digestion with bacterial collagenase. The 235, 165, 155, 145 and 93 kDa bands also resist degradation by cold, acidic pepsin. Amino acid analysis of whole tectorial membranes demonstrates that glycine accounts for nearly 25% of the total amino acid content, that proline, hydroxyproline and hydroxylysine are present and that amine sugars can be detected in fairly high concentrations. Estimates based on hydroxyproline content suggest that collagens account for 25-50% of the total tectorial membrane protein. Immunoblotting techniques demonstrate the presence of polypeptides cross reacting with antisera to Type II collagen, Type IX collagen and Type V collagen. Results from immunohistochemical studies confirm that these polypeptides are present in the tectorial membrane and are not contaminants of the isolation procedure. Collagenase treatment of tectorial membranes reveals the presence of an additional non-collagenous polypeptide with an apparent molecular weight of 173 kDa on 7.5% polyacrylamide gels, and polydisperse high molecular weight material spreading over a broad range at the top of the gels. This high molecular weight material and the 173, 60-73 and 35-49 kDa non-collagenous polypeptides are pepsin sensitive and all bind wheat germ agglutinin (WGA) suggesting that they contain N-acetyl glucosamine. The 173 kDa band also binds soybean agglutinin (SBA) suggesting the presence of N-acetyl galactosamine. In the absence of reducing agent the 173 and 60-73 kDa bands are no longer observed and high molecular weight material forming a broad band at the top of the separating gel is seen. The electrophoretic behaviour of this non-collagenous, glycosylated, disulphide bonded, high molecular weight material is altered by treatment with keratanase but not by chondroitinase ABC. The results of this study indicate the tectorial membrane contains at least three different collagen types and, in addition to these collagenous proteins, several non-collagenous, glycosylated polypeptides that may account for as much as 50% of the total tectorial membrane protein.
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PMID:Polypeptide composition of the mammalian tectorial membrane. 354 19

Conditioned culture media from confluent rabbit articular chondrocytes maintained in serum-free monolayer culture contained metal-dependent neutral pH collagenolytic activity degrading Type I, II and III rabbit [125I]-labeled collagens. This collagenolytic activity degraded Type II collagen more slowly than Type I collagen and Type III collagen at 37 degrees C. By contrast, collagenolysis by chondrocyte cytosolic protein, lysosomal granule protein and residual lysosomal membrane protein was highly specific for Type II collagen. Although collagenolytic activity against all the collagen isotypes tested was predominantly in a latent form after 24 h of culture, increasing levels of constitutive collagenolytic activity was measured with increasing culture time. These results are consistent with a differential degradation of rabbit interstitial collagens by rabbit chondrocyte collagenase. The data suggest a cellular compartmentalization of collagenolytic activity with specificity toward Type II collagen.
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PMID:Susceptibility of interstitial rabbit collagens to rabbit articular chondrocyte collagenase. 609 5

The salt glands of control and salt-stressed ducklings were dissociated with collagenase to produce cell aggregates or 'minilobules' which were cultured. The fine-structural organization of freshly isolated and cultured (up to 72 h) aggregates were examined and showed surprisingly intact fine-structural organization with minimal changes from untreated glands. Incorporation of [3H]leucine into total protein, membrane protein and immunoprecipitable Na,K ATPase was determined in cultures at various time points, by pulse or pulse-chase experiments. Incorporation of label was linear for 4 h in protein, but higher in cultures of salt-stressed glands than in controls. Na,K ATPase was synthesized throughout the time of the experiment, the rate being highest during the first 4 h, reaching a plateau by 24 h. Up to 10% of the total label was present in Na,K ATPase. These results are discussed with reference to the use of minilobule culture to analyse further synthesis and assembly during biogenesis and control of these processes.
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PMID:Organotypic cultures of the avian salt gland: biosynthesis of membrane proteins. 626 44

Adipose tissue is the principal site of extraglandular estrogen formation in nonpregnant women. The importance of adipose tissue as a site of estrogen formation is emphasized by the finding that increased body weight is associated with an increased incidence of endometrial carcinoma. In the present study, the kinetics of estrogen formation from androstenedione by adipocytes and by stromal cells isolated from human adipose tissue as well as by membrane fractions prepared from these cells were investigated. Subcutaneous adipose tissue samples obtained from women were dispersed by collagenase treatment, and aromatase activity was assayed by the incorporation of tritium from [1-3H]androstenedione into [3H]water. As previously reported, aromatase activity was found in intact stromal cells of adipose tissue, whereas little aromatase activity was detected in intact adipocytes. When crude membrane fractions (100,000 X g pellet) of stromal cells and adipocytes were incubated in the presence of [1-3H]androstenedione and an NADPH-generating system, however, aromatase activity was found in membrane fractions of both stromal cells and adipocytes, and estrogen formation increased in a linear manner as a function of time and membrane protein concentration. The apparent Michaelis constant (Km) of aromatase for androstenedione of intact stromal cells was 0.03 microM, whereas intact adipocytes did not convert androstenedione to estrone at substrate concentrations up to 3.0 microM. In membrane fractions of stromal cells, the rate of aromatization as a function of androstenedione concentration did not follow simple Michaelis-Menten kinetics, and both low affinity (Km = 1.03 microM) and high affinity (Km = 0.10 microM) components were observed. The affinity of androstenedione for aromatase of adipocyte membrane fractions was low; the rate of aromatization was not saturable at concentrations of androstenedione up to 3.0 microM. When intact adipocytes were incubated with [1-3H]androstenedione, then homogenized, and the homogenate was treated by differential centrifugation, the radioactivity that was added to the medium was found almost entirely in the lipid fraction of the cells. This finding is indicative that the low aromatase activity in intact adipocytes is the result of sequestration of steroid in lipid droplets in the cells. We suggest that the stromal cells of adipose tissue are a major source of the increased estrogen production in obese persons; a role for adipocytes in the regulation of adipose tissue estrogen formation, however, cannot be excluded at this time.
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PMID:Aromatase activity of membrane fractions of human adipose tissue stromal cells and adipocytes. 664 29

Parenchymal cells, isolated from normal adult rat liver (3 x 10(7) cells/g liver) by collagenase perfusion and maintained in nondividing monolayer culture, were employed to investigate cell surface properties of hepatocytes. Membrane transport systems for asialoorosomucoid (A-OM) and methotrexate (MTX) were lost rapidly in culture, whereas induction of tyrosine aminotransferase and transport of alpha-aminoisobutyrate actually increased during the first 3 days. Alterations in the membrane transport systems for A-OM and MTX reflected more generalized modifications of cell surface components induced during primary culture. Thus, the binding of concanavalin A(Con A) and wheat germ agglutinin (WGA) to cultured hepatocytes increased approximately 2-fold between 24 and 96 hr, and the incorportion of radioactive mannose and glucosamine into trichloroacetic acid-insoluble proteins increased 13-fold and 4-fold, respectively. Plasma membranes were isolated from cultured hepatocytes and the major structural proteins and glycoproteins were analyzed by SDS-polyacrylamide gel electrophoresis. Membrane instability between 24 and 96 hr of culture was characterized by time-dependent alterations in specific polypeptides and extensive changes in Con A- and WGA-binding glycoproteins. Although addition of a complex hormone supplement to the medium increased the number of viable cells and sustained A-OM and MTX transport systems for 24 hr, it had no influence on the altered membrane protein and glycoprotein profiles observed in its absence.
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PMID:Membrane characteristics of adult rat liver parenchymal cells in primary monolayer culture. 741 32


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