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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Src homology regions 2 (SH2) and 3 (SH3) are noncatalytic domains that are conserved among several proteins implicated in the regulation of cell proliferation. Using bacterially expressed fusion proteins containing the SH2 domain of the abl tyrosine kinase, we have quantitated the binding of these domains to the activated epidermal growth factor (EGF) receptor (EGFR). A 35S-labeled abl SH2 fusion protein binds to the human EGFR immunoprecipitated from EGF-treated NIH3T3 cells that overexpress the receptor. This binding is totally dependent on the pretreatment of cells with EGF. The interaction is rapid, reaching 50% of maximum within 1 min, and attaining apparent equilibrium by 10 min. Dissociation of the complex is biphasic with a rapidly dissociating component (t1/2 of less than 1 min), as well as a slowly dissociable component. The 35S-labeled abl SH2 fusion protein specifically binds to the EGFR in a saturable manner and is differentially inhibited by unlabeled fusion proteins containing SH2 domains from phospholipase C, the p85 subunit of phosphatidylinositol-3 kinase, and the GTPase activation protein of ras. To identify residues critical for abl SH2-EGFR binding, six point mutants were constructed in the highly conserved FLVRES motif. Three mutants (V170L, E172Q, and E174Q) display binding affinities similar to that of wild type. However, three other mutants (R171K, S173C, and S175C) have greatly reduced affinity. Interestingly, the binding affinity to the EGFR determined by the in vitro assay directly correlates with the transforming ability of the corresponding v-abl constructs in vivo (Mayer, B. J., Jackson, P. K., Etten, R. A. V., and Baltimore, D. (1992) Mol. Cell. Biol. 12, 609-618). These data indicate that the Arg-171, Ser-173, and Ser-175 are critical for both transformation and abl SH2 domain binding to phosphotyrosine-containing proteins.
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PMID:Direct analysis of the binding of the abl Src homology 2 domain to the activated epidermal growth factor receptor. 767 9

Beta 2-Microglobulin (beta 2 m) dissociated from surface HLA class I complex following exposure of cells to low pH and was detected in supernatant by radioimmunoprecipitation with specific monoclonal antibodies (mAbs). As the concn of beta 2m in supernatant increased, the binding of mAbs, specific for HLA class I heavy chains associated with beta 2m, to the cell surface declined. Binding of mAb specific for free HLA class I heavy chain to the cell surface increased after acid treatment. Reassociation with exogenous beta 2m confirmed increase in the number of free HLA class I heavy chains on surface of the cells after their exposure to low pH and also at least partially restored the reactivity with mAbs specific to HLA class I heavy chains associated with beta 2m. Dissociation of beta 2m from CD1 complex following acid treatment was also accompanied with the changes in antigenicity of cell surface CD1 molecules.
Mol Immunol 1993 Oct
PMID:Dissociation of beta 2-microglobulin is responsible for selective reduction of HLA class I antigenicity following acid treatment of cells. 769 38

Previous studies have shown that a combination of low pH and quercetin (QCT) treatment following heat shock markedly suppresses and delays the expression of heat shock protein genes, particularly the HSP70 gene (Lee et al., Biochem. Biophys. Res. Commun., 186:1121-1128, 1992). The possible mechanism for alteration of gene expression by treatment with QCT at low pH was investigated in human colon carcinoma cells. Cells were heated at 45 degrees C for 15 min and then incubated at 37 degrees C for various times (0-12 h) with QCT (0.05-0.2 mM) at pH 7.4 or 6.5. Gel mobility-shift analysis of whole cell extracts from heated cells showed the formation of the heat shock transcription factor (HSF)-heat shock element (HSE) complex. Dissociation of HSF from the HSE of the human HSP70 promotor occurred within 4 h under both pH conditions. The kinetics of recovery were not affected by treatment with 0.1% dimethyl sulfoxide (DMSO). However, the dissociation of HSF-HSE complex was markedly delayed during treatment with a combination of low pH and QCT. In addition, in vitro transcription assays showed a suppression of initiation and elongation of HSP70 mRNA. These results may explain why the combination of low pH and QCT treatment suppresses and delays the HSP70 gene expression as well as thermotolerance development.
Mol Cell Biochem 1994 Aug 31
PMID:Mechanism of quercetin-induced suppression and delay of heat shock gene expression and thermotolerance development in HT-29 cells. 784 88

We are developing a system for isolating tomato genes by transposon mutagenesis. In maize and tobacco, the transposon Activator (Ac) transposes preferentially to genetically linked sites. To identify transposons linked to various target genes, we have determined the RFLP map locations of Ac- and Dissociation (Ds)-carrying T-DNAs in a number of transformants. T-DNA flanking sequences were isolated using the inverse polymerase chain reaction (IPCR) and located on the RFLP map of tomato. The authenticity of IPCR reaction products was tested by several criteria including nested primer amplification, DNA sequence analysis and PCR amplification of the corresponding insertion target sequences. We report the RFLP map locations of 37 transposon-carrying T-DNAs. We also report the map locations of nine transposed Ds elements. T-DNAs were identified on all chromosomes except chromosome 6. Our data revealed no apparent chromosomal preference for T-DNA integration events. Lines carrying transposons at known map locations have been established which should prove a useful resource for isolating tomato genes by transposon mutagenesis.
Mol Gen Genet 1994 Mar
PMID:Analysis of the chromosomal distribution of transposon-carrying T-DNAs in tomato using the inverse polymerase chain reaction. 790 67

Cytoplasmic dynein is a minus-end-directed, microtubule-dependent motor composed of two heavy chains (approximately 530 kDa), three intermediate chains (approximately 74 kDa), and a family of approximately 52-61 kDa light chains. Although the approximately 530 kDa subunit contains the motor and microtubule binding domains of the complex, the functions of the smaller subunits are not known. Using two-dimensional gel electrophoresis and proteolytic mapping, we show here that the light chains are composed of two major families, a higher M(r) family (58, 59, 61 kDa; dynein light chain group A [DLC-A]) and lower M(r) family (52, 53, 55, 56 kDa; dynein light chain group B [DLC-B]). Dissociation of the cytoplasmic dynein complex with potassium iodide reveals that all light chain polypeptides are tightly associated with the approximately 530 kDa heavy chain, whereas the approximately 74 kDa intermediate chain polypeptides are more readily extracted. Treatment with alkaline phosphatase alters the mobility of four of the light chain polypeptides, indicating that these subunits are phosphorylated. Sequencing of a cDNA clone encoding one member of the DLC-A family reveals a predicted globular structure that is not homologous to any known protein but does contain numerous potential phosphorylation sites and a consensus nucleotide-binding motif.
Mol Biol Cell 1994 Jun
PMID:Characterization of DLC-A and DLC-B, two families of cytoplasmic dynein light chain subunits. 794 21

We have expressed and purified a series of recombinant zinc finger polypeptides derived from the cDNA for the Xenopus 5 S gene-specific transcription factor TFIIIA. Dissociation constants for the interaction of each of the truncated polypeptides with the 5 S gene promoter have been measured using gel mobility shift assays. DNase I footprinting and proteolysis experiments provide additional insights into the interactions of individual fingers within complexes of the truncated proteins. These results are discussed in terms of recently proposed models for the TFIIIA-DNA interaction. The effects of mutations in two of the strongly binding proteins, zf1-3 and zf1-7, on DNA binding affinity have been investigated. Mutations have been made both in putative DNA-contact residues and in the linker regions between zinc fingers. The observed decreases in binding affinity cannot be explained simply in terms of loss of protein-DNA contacts. Our results support a model in which DNA binding is accomplished through sets of interacting zinc fingers that make different energetic contributions to the overall binding of the protein and different contacts with the DNA.
J Mol Biol 1994 Nov 18
PMID:Relative contributions of the zinc fingers of transcription factor IIIA to the energetics of DNA binding. 796 19

A protein consisting of 60 kDa subunits (As-P60) was isolated from etiolated oat seedlings (Avena sativa L.) and characterized as avenacosidase, a beta-glucosidase that belongs to a preformed defence system of oat against fungal infection. The enzyme is highly aggregated; it consists of 300-350 kDa aggregates and multimers thereof. Dissociation by freezing/thawing leads to complete loss of enzyme activity. The specificity of the enzyme was investigated with para-nitrophenyl derivatives which serve as substrates, in decreasing order beta-fucoside, beta-glucoside, beta-galactoside, beta-xyloside. The corresponding orthonitrophenyl glycosides are less well accepted. No hydrolysis was found with alpha-glycosides and beta-thioglucoside. An anti-As-P60 antiserum was prepared and used for isolation of a cDNA clone coding for As-P60. A presequence of 55 amino acid residues was deduced from comparison of the cDNA sequence with the N-terminal sequence determined by Edman degradation of the mature protein. The presequence has the characteristics of a stroma-directing signal peptide; localization of As-P60 in plastids of oat seedlings was confirmed by western blotting. The amino acid sequence revealed significant homology (> 39% sequence identity) to beta-glucosidases that are constituents of a defence mechanism in dicotyledonous plants. 34% sequence identity was even found with mammalian and bacterial beta-glucosidases of the BGA family. Avenacosidase extends the occurrence of this family of beta-glucosidases to monocotyledonous plants.
Plant Mol Biol 1994 Nov
PMID:Avenacosidase from oat: purification, sequence analysis and biochemical characterization of a new member of the BGA family of beta-glucosidases. 800 4

The process of reversible membrane association of the nuclear-encoded heat-shock protein hsp22 in Chlamydomonas reinhardtii cells during recovery from heat stress has been investigated. hsp22 associates with a chloroplast membrane-enriched fraction, dissociates from the membranes during recovery from heat shock and rebinds during a subsequent heat-shock treatment in vivo. The protein remains in the cell soluble fraction for at least 22 h after heat-stress treatment. Dissociation of membrane-bound hsp22 occurs only at 25-38 degrees C and reassociation occurs only at the hsp22 induction temperature (38-42 degrees C). Hsp22 dissociation from the membrane fraction is not related to de novo protein synthesis in vivo and does not occur in vitro. Based on the derived amino acid sequence, hsp22 is not considered a typical chloroplast-associated heat-shock protein [Vierling, E. (1991) Annu. Rev. Plant Physiol. Plant Mol. Biol. 42, 579-620] and may be associated with the chloroplast envelope membrane. However, the reversible association of hsp22 with the chloroplast-enriched membrane fraction indicates similar properties to those of pea low-molecular-mass heat-shock proteins [Glaczinski, H. & Kloppstech, K. (1988) Eur. J. Biochem. 173, 579-583] and may be related to the transient response of the chloroplast to heat stress.
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PMID:Reversible membrane association of heat-shock protein 22 in Chlamydomonas reinhardtii during heat shock and recovery. 802 82

We have introduced a genetically marked Dissociation transposable element (DsHPT) into tomato (Lycopersicon esculentum) by Agrobacterium tumefaciens-mediated transformation. Probes for the flanking regions of the T-DNA and transposed DsHPT elements were obtained with the inverse polymerase chain reaction (IPCR) technique and used in RFLP linkage analyses. The RFLP map location of 11 T-DNAs carrying DsHPT was determined. The T-DNAs are distributed on 7 of the 12 tomato chromosomes. To explore the feasibility of gene tagging strategies in tomato using DsHPT, we examined the genomic distribution of DsHPT receptor sites relative to the location of two different, but very closely linked, T-DNA insertion sites. After crosses with plants expressing Ac transposase, the hygromycin phosphotransferase (HPT) marker on the Ds element and the excision markers beta-glucuronidase (GUS) and Basta resistance (BAR) facilitated the identification of plants bearing germinally transposed DsHPT elements. RFLP mapping of 21 transposed DsHPT elements originating from the two different T-DNA insertions revealed distinct patterns of reintegration sites.
Mol Gen Genet 1994 Jun 15
PMID:Transgenic tomato lines containing Ds elements at defined genomic positions as tools for targeted transposon tagging. 802 83

Antibiotic resistance genes can act as either cell autonomous or non-cell autonomous genetic markers with which to monitor the excision of plant transposons. To convert spectinomycin resistance from a non-cell autonomous resistance to cell autonomous resistance, a transit peptide for chloroplast localization from a petunia ribulose bisphosphate carboxylase (rbcS) gene was fused in-frame to the aadA gene, which confers spectinomycin and streptomycin resistance. Constructs were generated in which the expression of this chimeric gene was prevented by the presence, in the 5' untranslated leader, of the maize transposons Activator (Ac) or Dissociation (Ds). When progeny of tobacco or tomato plants transformed with these constructs were germinated on spectinomycin-containing medium, germinally revertant and somatically variegated individuals could be distinguished.
Mol Gen Genet 1994 Jul 25
PMID:Chloroplast targeting of spectinomycin adenyltransferase provides a cell-autonomous marker for monitoring transposon excision in tomato and tobacco. 805 38


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