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)

The protein composition of two influenza A virus strains from different serological groups was studied. For preliminary separation of envelope and core proteins the virus was treated with nonionic detergent Triton X-100 solution followed by chromatography in ultragel AcA 34. After their separation by disk electrophoresis and treatment with trypsin they were labeled with tritium and peptide analysis was carried out. Differences in peptide maps between the appropriate light and heavy chains of hemagglutinins of the strains under study were demonstrated. Differences in the composition of nucleoprotein and matrix protein were insignificant.
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PMID:[Peptide mapping of the major proteins in 2 strains of influenza virus]. 392 20

Nuclear matrix prepared from bovine lymphocytes contained a significant amount of actin. Both nuclear matrix actin and rabbit muscle actin showed the same electrophoretic mobility on SDS-gel. The matrix-associated actin could be separated into three isoproteins which may correspond to alpha-, beta- and gamma-actin. The most acidic spot of these isoproteins co-migrated with rabbit muscle actin (alpha-actin) on two-dimensional electrophoresis. The amino-acid composition of the nuclear matrix actin was closely related to that of rabbit muscle and to that of porcine brain actin. Moreover, the actin filaments, treated with 0.75 M guanidine hydrochloride, changed from the polymerized form of the nuclear matrix actin into a monomeric form (G-actin), which had strong inhibitor activity against pancreatic DNase I. From this inhibition, the actin content of the nuclear matrix was estimated to be about 12% of total matrix protein. When the nuclear matrix was digested with trypsin, the bulk of matrix protein was hydrolyzed, but about 80% of the actin remained associated with sphere structures (trypsin-treated nuclear matrix) precipitable by low speed centrifugation. SDS-gel analysis revealed that actin was one of the major components of the trypsin-treated nuclear matrix, which had a similar size and structure as the untreated nuclear matrix. The fibrogranular structure and residual nucleoli of the original nuclear matrix were well preserved against trypsin digestion; however, the peripheral lamina was removed. These results indicate that the matrix-associated actin is localized predominantly in the matrix interior, where it presumably interacts closely with the fibrogranular structure and/or the residual nucleoli.
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PMID:Association of actin with the nuclear matrix from bovine lymphocytes. 621 95

A pseudo-crystalline array of subunits has been observed on particles of the La Sota, in contrast to the Ulster , strain of Newcastle disease virus (NDV) grown in MDBK tissue culture without trypsin. This regular arrangement of subunits was associated with the semi-permissive nature of the tissue culture system, as it disappeared when trypsin, which allows infectious virus to be made, was added. The phenomenon described was considered to be related to the crystalline array of matrix protein which has been described inside the envelope of Sendai virus and NDV by others.
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PMID:A regular subunit pattern seen on non-infectious Newcastle disease virus particles. 672 84

The HMV-II cells infected with influenza C virus were labeled with inorganic [32P]phosphate to identify phosphorylated proteins. Analysis by radioimmunoprecipitation with antiviral serum or monoclonal antibodies revealed that three major structural proteins of the virus, hemagglutinin-esterase (HE), nucleoprotein (NP), and matrix protein (M1) are all phosphorylated in both infected cells and virions. It was also observed that, in the presence of trypsin (10 micrograms/ml), the unphosphorylated form of the HE glycoprotein was cleaved efficiently whereas the phosphorylated form was not, raising the possibility that phosphorylation of HE may influence its susceptibility to degradation by proteolytic enzymes.
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PMID:Identification of influenza C virus phosphoproteins. 857 90

As a first step in understanding the calcification mechanism, a matrix protein in the gastrolith of the crayfish Procambarus clarkii was purified and sequenced. The protein was insoluble in acid, but after trypsin digestion, it dissolved in 6 M urea. The trypsin-digested protein dissolved in urea solution was purified by reversed-phase HPLC and designated gastrolith matrix protein fragment. The fragment had a molecular weight of 9658 and a blocked amino terminus. It had tandemly repeated units not reported before at the central part of the sequence, with each unit being Gly-Ser-X1-X2-Phe as the most typical sequence. This peptide was found associated with chitin, a main component of the organic matrix.
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PMID:Characterization of a matrix protein in the gastroliths of the crayfish Procambarus clarkii. 898 97

Cartilage oligomeric matrix protein (COMP) is a high-molecular-weight glycoprotein found at a high concentration in articular cartilage. Recent studies have shown that the joint fluid and serum levels of antigenic COMP, measured by an enzyme-linked immunosorbent assay (ELISA) which uses a polyclonal antiserum raised against bovine COMP, provide important information about metabolic changes occurring in the cartilage matrix in joint disease. In this report, we describe the specificity of three monoclonal antibodies (mAbs) to human COMP and their usefulness in quantifying antigenic COMP fragments in body fluids. Two of the mAbs (16-F12 and 18-G3) recognized both oligomeric and monomeric forms of COMP, but the third (17-C10) reacted positively only with the former. Immunoblots of human COMP, predigested with trypsin for up to 6 h, showed that the three mAbs are directed against different epitopes identified on small tryptic fragments of 30 kDa (16-F12), 25 kDa (17-C10), and 40 kDa as well as 30 kDa (18-G3), respectively. The antibodies also recognized a different pattern of fragments in human pathological synovial fluids. This was particularly striking in the case of the medium size fragments (16-F12: 90 and 110 kDa; 17-C10: 70 and 90 kDa; 18-G3: up to five bands from 70 to 130 kDa). Competitive indirect inhibition ELISAs developed with mAbs 16-F12 and 17-C10 revealed further differences in the specificities of these antibodies. Thus, while mAb 16-F12 can be used only to quantify antigenic COMP in human synovial fluid and serum, mAb 17-C10 is useful in addition when analyzing canine and horse synovial fluid as well as canine serum. The results of analyses of synovial fluid samples from patients with osteoarthritis and rheumatoid arthritis provided preliminary evidence in support of the contention that measurement of the different COMP epitopes recognized by these mAbs in body fluids could prove useful in the clinical assessment of patients with joint disease.
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PMID:Characterization of monoclonal antibodies recognizing different fragments of cartilage oligomeric matrix protein in human body fluids. 914 47

We have previously identified two distinct forms of putative viral assembly intermediate complexes, a detergent-resistant complex (DRC) and a detergent-sensitive complex (DSC), in human immunodeficiency virus type 1 (HIV-1)-infected CD4(+) T cells (Y. M. Lee and X. F. Yu, Virology 243:78-93, 1998). In the present study, the intracellular localization of these two viral assembly intermediate complexes was investigated by use of a newly developed method of subcellular fractionation. In wild-type HIV-1-infected H9 cells, the DRC fractionated with the soluble cytoplasmic fraction, whereas the DSC was associated with the membrane fraction. The DRC was also detected in the cytoplasmic fraction in H9 cells expressing HIV-1 Myr- mutant Gag. However, little of the unmyristylated Gag and Gag-Pol proteins was found in the membrane fraction. Furthermore, HIV-1 Gag proteins synthesized in vitro in a rabbit reticulocyte lysate system in the absence of exogenous lipid membrane were able to assemble into a viral Gag complex similar to that of the DRC identified in infected H9 cells. The density of the viral Gag complex was not altered by treatment with the nonionic detergent Triton X-100, suggesting a lack of association of this complex with endogenous lipid. Formation of the DRC was not significantly affected by mutations in assembly domains M and L of the Gag protein but was drastically inhibited by a mutation in the assembly I domain. Purified DRC could be disrupted by high-salt treatment, suggesting electrostatic interactions are important for stabilizing the DRC. The Gag precursor proteins in the DRC were more sensitive to trypsin digestion than those in the DSC. These findings suggest that HIV-1 Gag and Gag-Pol precursors assemble into DRC in the cytoplasm, a process which requires the protein-protein interaction domain (I) in NCp7; subsequently, the DRC is transported to the plasma membrane through a process mediated by the M domain of the matrix protein. It appears that during this process, a conformational change might occur in the DRC either before or after its association with the plasma membrane, and this change is followed by the detection of virus budding structure at the plasma membrane.
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PMID:Formation of virus assembly intermediate complexes in the cytoplasm by wild-type and assembly-defective mutant human immunodeficiency virus type 1 and their association with membranes. 1036 15

Mutations in residues in the type 3 calcium-binding repeats and COOH-terminal globular region of cartilage oligomeric matrix protein (COMP) lead to two skeletal dysplasias, pseudoachondroplasia and multiple epiphyseal dysplasia. It has been hypothesized that these mutations cause COMP to misfold and to be retained in the endoplasmic reticulum. However, this hypothesis is not supported by previous reports that COMP, when purified in the presence of EDTA, shows no obvious difference in electron microscopic appearance in the presence or absence of calcium ions. Since this discrepancy may be due to the removal of calcium during purification, we have expressed wild-type COMP and the most common mutant form found in pseudoachondroplasia, MUT3, using a mammalian expression system and have purified both proteins in the presence of calcium. Both proteins are expressed as pentamers. Direct calcium binding experiments demonstrate that wild-type COMP, when purified in the presence of calcium, is a calcium-binding protein. Rotary shadowing electron microscopy and limited trypsin digestion at various calcium concentrations show that there are conformational changes associated with calcium binding to COMP. Whereas COMP exists in a more compact conformation in the presence of calcium, it shows a more extended conformation when calcium is removed. MUT3, with a single aspartic acid deletion in the type 3 repeats, binds less calcium and presents an intermediate conformation between the calcium-replete and calcium-depleted forms of COMP. In conclusion, we show that a single mutation in the type 3 repeats of COMP causes the mutant protein to misfold. Our data demonstrate the importance of calcium binding to the structure of COMP and provide a plausible explanation for the observation that mutations in the type 3 repeats and COOH-terminal globular region lead to pseudoachondroplasia.
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PMID:Cartilage oligomeric matrix protein is a calcium-binding protein, and a mutation in its type 3 repeats causes conformational changes. 1085 28

The involvement of rat liver mitochondria in the flavinylation of the mitochondrial matrix flavoenzyme dimethylglycine dehydrogenase (Me2GlyDH) has been investigated. Me2GlyDH was synthesized as an apoenzyme in the rabbit reticulocyte lysate (RL) transcription/translation system and its flavinylation was monitored by virtue of the trypsin resistance of the holoenzyme. The rate of holoenzyme formation in the presence of FAD was stimulated with increasing efficiency by the addition of solubilized mitoplasts, mitochondrial matrix and DEAE-purified matrix fraction. Apo-Me2GlyDH was also converted into holoenzyme when the solubilized mitoplasts were supplemented with FMN and ATP. This observation is consistent with the existence of a mitochondrial FAD synthetase generating the FAD needed for holoenzyme formation from its precursors. Holoenzyme formation in the presence of FAD increased linearly with the concentration of matrix protein in the assay, and depended on the amount of externally added Me2GlyDH with saturation characteristics. These findings suggest the presence of a protein factor in the mitochondrial matrix which stimulates Me2GlyDH flavinylation. This factor was different from both mitochondrial heat shock protein (Hsp)70, as shown by immunodepletion experiments, and mitochondrial Hsp60, as demonstrated by the capability of a DEAE-purified matrix fraction devoid of Hsp60 to accelerate flavinylation of both RL translated and purified Me2GlyDH.
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PMID:A protein factor of rat liver mitochondrial matrix involved in flavinylation of dimethylglycine dehydrogenase. 1088 Sep 57

We have analysed the expression and cellular localisation of the matrix protein VP40 from Ebola virus. Full-length VP40 and an N-terminal truncated construct missing the first 31 residues [VP40(31-326)] both locate to the plasma membrane of 293T cells when expressed transiently, while a C-terminal truncation of residues 213 to 326 [VP40(31-212)] shows only expression in the cytoplasm, when analysed by indirect immunofluorescence and plasma membrane preparations. In addition, we find that full-length VP40 [VP40(1-326)] and VP40(31-326) are both released into the cell culture supernatant and float up in sucrose gradients. The efficiency of their release, however, is dependent on the presence of the N-terminal 31 residues. VP40 that is released into the supernatant is resistant to trypsin digestion, a finding that is consistent with the formation of viruslike particles detected by electron microscopy. Together, these results provide strong evidence that Ebola virus VP40 is sufficient for virus assembly and budding from the plasma membrane.
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PMID:Vesicular release of ebola virus matrix protein VP40. 1131 56


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