Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0153470 (Spleen)
 4,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytotoxic T lymphocytes (CTL) play an important role in recovery from a number of viral infections. They are also implicated in virus-induced immunopathology as best demonstrated in lymphocytic choriomeningitis virus (LCMV) infection of adult immunocompetent mice. In the present study, the structure of the T-cell receptor (TCR) in LCMV-specific CTL in C57BL/6 (B6) mice was investigated. Spleen T cells obtained from LCMV-infected mice were cultured in vitro with virus-infected stimulator cells and then stained with anti-TCR V beta antibodies. A skewing of V beta usage was noticeable in T cells enriched for their reactivity to LCMV, suggesting that particular V segments are important for the recognition of LCMV T-cell epitopes in B6 mice. To gain more detailed information on the structure of the TCR specific for LCMV epitopes, we studied CTL clones. It has been shown that approximately 90% of LCMV-reactive CTL clones generated in H-2b mice are specific for a short peptide fragment of the LCMV glycoprotein, residues 278 to 286, recognized in the context of the class I major histocompatibility complex molecule, Db. Four CTL clones possessing the specificity were randomly selected from a collection of clones, and their TCR genes were isolated by cDNA cloning or by the anchored polymerase chain reaction. All four clones were found to use V alpha gene segments belonging to the V alpha 4 subfamily. By RNA blot analysis, two more clones with the same specificity were also shown to express the V alpha 4 mRNA. In contrast, three different V beta gene segments were used among the four clones examined. J beta 2.1 was used by three of the clones. Although amino acid sequences in the V(D)J junctional regions were dissimilar, aspartic acid was found in the V alpha J alpha and/or V beta D beta J beta junctions of all four of these clones, suggesting that this residue is involved in binding the LCMV fragment. Restricted usage of V alpha and possibly J beta segments in the CTL response to a major T-cell epitope of LCMV raises the possibility that immunopathology in LCMV infection can be treated with antibodies directed against such TCR segments. Thus, similar analysis of the TCR in other virus infections is warranted and may lead to therapeutic strategies for immunopathology due to virus infections.
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PMID:Restricted V-segment usage in T-cell receptors from cytotoxic T lymphocytes specific for a major epitope of lymphocytic choriomeningitis virus. 170 Aug 30

Comparison of amino acid sequences of the alpha-chain fragment of human C4, C4d, has shown C4A- and C4B-specific sequences at residues 1101-1106 in which the aspartic acid-histidine substitution at position 1106 may be related to the amide and ester bond forming properties of these molecules. Peptides containing twelve amino acid residues of the C4A- or C4B-specific sequences were synthesized and injected into female Balb/c mice. Serum from 2 mice, one immunized with the C4A-specific peptide and the other with the C4B-specific peptide, gave strong isotype-specific responses in an enzyme-linked immunosorbent assay against affinity-purified C4A3 and C4B2B1. Spleen cells from these mice were fused with the mouse myeloma SP2/0-Ag 14, and two cloned cell lines, AII-1 and BII-1, were established from hybrids. Enzyme-linked immunosorbent assay and western blotting of monoclonal antibodies AII-1 and BII-1 show that the former reacts with the C4A but not with the C4B alpha-chain and the latter with C4B but not with the C4A alpha-chain. Furthermore, immunoblotting of C4 allelic variants showed that AII-1 reacted with all C4A allotypes tested, including A6, A4, A3 and A2, whereas BII-1 reacted with all C4B allotypes tested, including B5, B3, B2, and B1.
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PMID:Monoclonal antipeptide antibodies against amino acid residues 1101-1106 of human C4 distinguish C4A from C4B. 204 34

Using a synthetic peptide (Glu-Asp-Ala-Glu-Tyr-Ala-Ala-Arg-Arg-Arg-Gly) as a substrate, various normal tissues from the rat were probed for tyrosine protein kinase activity. Spleen was shown to contain much higher tyrosine protein kinase activity than other rat tissues (lung, brain, testes, liver, kidney, heart, and thymus, in decreasing order of specific activity). Most of the tyrosine protein kinase activity of the various rat tissues (greater than 80%) was present in the particulate fraction, and Nonidet P-40, a nonionic detergent, could activate the particulate form of the enzyme 2-20-fold in many of the tissues. Epidermal growth factor (1 microgram/ml), cyclic AMP, cyclic GMP, or Ca2+ did not increase spleen tyrosine protein kinase activity. Half-maximal enzyme activity was observed at 60-80 microM MgATP and at 2.2 mM peptide, and both Mg2+ (10 mM) and Mn2+ (0.5-1.0 mM) were effective divalent metal ions for the expression of activity. When the particulate fraction of spleen was incubated with [gamma-32P]ATP followed by polyacrylamide gel electrophoresis in the presence of Na dodecyl SO4, a number of alkali-stable bands were identified by autoradiography. Two major bands at Mr = 53,000 and 56,000 were shown to contain phosphotyrosine. Two similar alkali-stable bands containing phosphotyrosine but with lower amounts of 32P labeling were also observed in the particulate fractions of various other tissues (lung, brain, kidney, and testes). The particulate form of tyrosine protein kinase of rat spleen could be solubilized by using high concentrations of Nonidet P-40 (5%) at an alkaline pH (pH 9.0). Partial purification and subsequent filtration on Sephacryl S-200 yielded a peak of tyrosine protein kinase activity with an apparent molecular weight of 55,000. The two major phosphorylated bands of Mr = 53,000 and 56,000 co-migrated with the peak of enzyme activity. The solubilized and partially purified enzyme preparation phosphorylated only tyrosine residues when either endogenous proteins or casein were used as substrates. These results suggest that relatively high activities of tyrosine protein kinase exist in a normal tissue (rat spleen). Major endogenous substrates of the enzyme(s) appear to be represented by two proteins of Mr = 53,000 and 56,000; one or both of these substrates may be the tyrosine protein kinase itself.
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PMID:Tyrosine protein kinase activity of rat spleen and other tissues. 668 16

Spleen necrosis virus (SNV) is an amphotropic type C retrovirus originally isolated from a duck. The envelope protein is related to that of type D retroviruses, and SNV appears to use the same receptor as do simian retroviruses. However, little is known about envelope-receptor interactions of SNV. We constructed a series of envelope mutants to characterize the SU peptide of SNV. Point mutations were introduced throughout SU in regions that are conserved among all retroviruses belonging to the same receptor interference group. The biological and biochemical properties of these mutants were analyzed. All mutants were transported efficiently to the cell surface. Almost all mutations in the amino-terminal one-third caused a conformational change of the envelope and a significant drop in infectivity and abolished the ability to confer superinfection interference. Similar observations were made with only two of seven mutants with mutations in the middle of SU. Four mutations in this region had little or no effect on biological activity. One mutant envelope protein (Asp to Arg at position 192) was processed normally but showed little infectivity and had no ability to confer superinfection interference. A detailed mutational analysis suggested that this amino acid forms a hydrogen bond to its cellular receptor. Mutations within the carboxy-terminal part of SU had very little or no effect on biological function. Aberrantly processed envelope proteins were proteolytically cleaved at a new point upstream of and differing in sequence from the conserved retroviral SU/TM cleavage site. Surprisingly, these mutants still retained some infectivity (0.01 to 1% of that of the wild type). Our data indicate that the envelope of SNV behaves in a manner very different from that of the envelopes of other studied retroviruses.
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PMID:Mutational analysis of the envelope protein of spleen necrosis virus. 870 26