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:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 60,000-dalton polypeptide (p60) has been identified in the feline leukemia virus (FeLV) pseudotype of Moloney sarcoma virus [MSV(FeLV)]. This polypeptide is present in the purified virus complex in concentrations greater than either the murine p30 or the feline p27. Purified p60 crossreacts immunologically with murine p30 group antiserum and contains several interspecies determinants, whereas the group specific determinant of FeLV p27 is not detected. Comparison of peptide fingerprints of p60 and murine p30 show many peptides in common. Limited digestion of p60 with either trypsin or chymotrypsin produced p30-35 and p20 peptides which retain the MuLV p30 group and interspecies antigenic activities. The p30 produced by both enzymes comigrates in polyacrylamide gels with the murine p30 of MSV(FeLV), thus suggesting that p60 may be an uncleaved precursor to p30.
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PMID:A p60 polypeptide in the feline leukemia virus pseudotype of Moloney sarcoma virus with murine leukemia virus p30 antigenic determinants. 4 60

Chicken fibroblasts derived from the H & N flock, which have been characterized as resistant to subgroup B avian oncornaviruses in focus assays, can be infected in suspension shortly after trypsinization by subgroup B sarcoma and leukosis viruses. Once cells are plated, resistance to infection reappears rapidly. C/BE cell suspensions obtained by treatment with EDTA instead of trypsin are not as sensitive to infection. Late interference established by preinfection with subgroup B leukosis viruses is not overcome by trypsinization. In addition to C/BE H & N chicken cells, C/ABE RPRL line 7 cells can also be infected by subgroup B viruses shortly after trypsinization; however, none of the cell types can be made sensitive to subgroup E infection. These results are discussed in relation to current information on the genetic control of resistance to avian oncornaviruses.
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PMID:Infection of resistant avian cells by subgroup B Rous sarcoma virus. 18 23

Thrombin stimulates cell proliferation in cultures of normal chick embryo fibroblasts but not in cells transformed with Rous sarcoma virus. Analysis of medium conditioned by Rous-sarcoma-virus-transformed cultures demonstrates that these cells do not secrete molecules that can inhibit or inactivate thrombin. The interaction of thrombin with these cells was investigated with enzymatically active 125I-thrombin. The amount of cell-associated 125I-thrombin was found to be three times greater with normal cells than with transformed cells. In both types of cell, greater than 50% of the total cell-associated 125I-thrombin was found as a component that was not dissociated from the cells by trypsin treatment, an observation suggesting that a significant portion was not on the cell surface. The amount of the trypsin-insensitive fraction increases with time up to 12 hr, whereas the trypsin-sensitive fraction is saturated after 1-4 hr. Autoradiography of thin sections of 125I-thrombin-treated cells observed by electron microscopy reveals that after 10 hr incubation greater than 70% of the label is localized in the cytoplasm of both normal and transformed cells. Autoradiograms of sodium dodecyl sulfate/polyacrylamide slab gels demonstrate that 40% of the intracellular label is the size of native thrombin with the remainder in two large fragments of 22,000 and 19,500 daltons.
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PMID:Binding and internalization of thrombin by normal and transformed chick cells. 19 17

Murine sarcoma virus-transformed mouse fibroblasts produce polypeptide growth factors and release them into serum-free medium. These factors stimulate cells to divide in monolayer cultures and also to form colonies that grow progressively soft agar. Three major peaks of activity are seen, with apparent molecular weights of 25,000, 12,000, and 7000. The sarcoma growth factors are heat-stable, trypsin-sensitive, and active in nanogram quantities when tested for growth stimulation of untransformed rat and mouse fibroblasts. All three molecular species are also capable of competing for membrane epidermal growth factor (EGF) receptors when tested with 125I-labeled EGF. They differ from mouse EGF, however, in their molecular weights, in their inability to react with anti-EGF antibodies, and in their ability to convert cells to anchorage independent (agar) growth. For the above reasons, we conclude that the sarcoma growth factors are a new class of polypeptide tropic factors that confer on fibroblasts in vitro properties associated with the transformed phenotype.
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PMID:Growth factors from murine sarcoma virus-transformed cells. 21 12

Antibodies to fibronectin and to distinct types of procollagens and collagens were used in immunofluorescent staining to localize these proteins in cell cultures. Normal human skin or lung fibroblasts produced a fibrillar pericellular matrix in which fibronectin and procollagen (types I and III) showed extensive codistribution. Fibronectin and procollagen were synthesized by the same cells as judged by double-stain immunofluorescence. Pericellular procollagen was specifically digested with collagenase without an effect on the fibrillar distribution of matrix fibronectin. Brief treatment with trypsin removed both matrix proteins. The human tumor cell lines HT-1080 (fibrosarcoma) and RD (rhabdomyosarcoma) produced little or no matrix fibronectin or procollagen. At sites of cell contact, simian virus 40-transformed lung fibroblasts (VA13) produced small amounts of pericellular fibrillar matrix fibronectin that codistributed with procollagen type I. Intracellular fibronectin and procollagen were visualized in all of these human sarcoma cell lines. When chicken embryo fibroblasts infected with a T class mutant (NY68) of Rous sarcoma virus temperature-sensitive for transformation were maintained at the nonpermissive temperature (41 degrees ) the cells had normal phenotype and a fibrillar matrix containing fibronectin and procollagen was present. At the permissive temperature (35 degrees ), the cells showed transformed phenotype and the matrix was lost. The failure to produce a pericellular fibronectin/collagen matrix may account for several phenotypic characteristics of transformed cultured fibroblasts.
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PMID:Codistribution of pericellular matrix proteins in cultured fibroblasts and loss in transformation: fibronectin and procollagen. 21 6

Colony-stimulating factors (CSF) active on both human and murine bone marrow colony-forming units in culture (CFU-C) were found in the conditioned medium of Yoshida sarcoma cells (line YSSF-212T), although the cells originated from rats. The CSF were inactivated by digestion with trypsin, alpha-chymotrypsin, and pronase. By chromatography on DEAE-cellulose, the CSF were separated into five subgroups with different capacities to stimulate mouse granulocyte and macrophage progenitors. CSF in these five peaks were eluted from an Ultrogel AcA 44 gel filtration column with apparent molecular weights of 22,000-25,000 daltons. CSF of nonhuman origin stimulating human CFU-C would be useful in hematologic studies of bone marrow cells.
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PMID:Colony-stimulating factors active on human bone marrow cells from a Yoshida sarcoma cell line. 30 93

Regional (popliteal) lymph node cells (RLNC) from A/Jax mice, inoculated in each hind foot with isogeneic Sarcoma 1 tumor cells, demonstrated cytotoxicity in vitro at Day 14 of tumor growth but lost this ability by Day 21. These noncytotoxic RLNC were capable of suppressing activity of other cytotoxic lymphoid cells, but after incubation for 24 hr in vitro their cytotoxicity was restored and their suppressive activity was abrogated. RLNC responsible for cytotoxicity were removed by treatment with anti-theta serum plus complement. The suppressive effect of RLNC was found to be mediated by a soluble "blocking" factor which was released into the culture medium after 24 hr incubation. The factor was not detected in culture media from RLNC pretreated with anti-theta serum plus complement prior to incubation. Absorption of RLNC culture supernatants with tumor-bearer spleen cells, but not with normal spleen cells, completely removed the blocking factor, while absorption by Sarcoma 1 cells significantly reduced blocking activity. The factor was trypsin sensitive, was retained on an Amicon XM100 filter, and did not demonstrate the presence of antibody to Sarcoma 1 in a radioimmunoassay. Although the exact nature of the factor has not been established, it appears to be a receptor antigen complex from T-cells of tumor-bearing animals.
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PMID:Immunological activity of regional lymph nodes in tumor-bearing mice. 31 91

A clone, YS-T22, of cells from Yoshida sarcoma cell line, YSSF-212T, grown in "serum-free" culture medium produced factors stimulating differentiation of mouse myeloid leukemia cells (M1) to macrophages and granulocytes. The formation of macrophages and granulocytes was accompanied by induction of phagocytosis, locomotive activity, and lysosomal enzyme activities. The rates of induction of these differentiated phenotypes were proportional to the concentration of the factor added and the period of treatment. The factor stimulating differentiation of M1 cells was a heat-labile, nondialyzable proteinaceous substance that was inactivated by trypsin but not by ribonuclease or glycosidases. On diethylaminoethyl cellulose chromatography, the factor stimulating differentiation of M1 cells from conditioned medium of YS-T22 cells was eluted in various fractions with or without activity of the colony-stimulating factor.
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PMID:Characterization of factors stimulating differentiation of mouse myeloid leukemia cells from a Yoshida sarcoma cell line cultured in serum-free medium. 31 74

Intranuclear filaments aggregating into rodlike structures were found in cells of an undifferentiated soft tissue sarcoma in a child. Similar structures have been uncommonly described in human neoplasms, and uncertainties exist concerning the nature of the inclusion bearing cells in previous reports. The filaments were found to be resistant to mild trypsin digestion. Review of the pertinent literature indicates that these structures may represent the structural manifestation of a highly specialized functional state, rather than a degenerative phenomenon or an artifact. A certain selectivity of occurrence has also been noted. It is therefore plausible to speculate that intranuclear filaments may eventually constitute a morphologic criterion of interest for new tumor classifications.
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PMID:Intranuclear filaments in a soft tissue sarcoma. 64 Jun 44

Nucleosomes isolated from Yoshida sarcoma chromatin by micrococcal nuclease treatment were relatively inactive as templates for in vitro DNA synthesis. However, the template activity increased by trypsin digestion of nucleosomes or addition of heparin to the reaction mixture. This indicates that the nucleosomal template activity is masked. A crude extract of Yoshida sarcoma cells stimulated the nucleosomal template activity. The stimulatory factor was separated into three peaks by DEAE cellulose column chromatography. The same three peaks were observed in normal rat liver extract with much lower activities, but enhanced in regenerating liver. The factors seem to stimulate DNA synthesis by activating DNA template in nucleosomes without degrading histones or changing the primary structure of nucleosomal DNA.
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PMID:Cellular factors for stimulation of nucleosomal template activity for in vitro DNA synthesis. 70 Dec 34


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