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Query: UMLS:C0155339 (Brown)
 12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activation of the human transferrin receptor promoter by mitogenic stimulation of quiescent cells is a delayed event that reaches a maximum several hours after stimulation. Previous results have defined a region of the transferrin receptor gene promoter that is required for increased expression in mitogen-activated cells (W. K. Miskimins and D. B. Brown, Exp. Cell Res., 191: 328-331, 1990; Q. Ouyang et al., Mol. Cell. Biol., 13: 1796-1804, 1993). This region contains two elements (elements A and B) that appear to cooperate in the response to mitogenic stimulation. Serum stimulation of quiescent cells leads to the induction of nuclear factors that bind to both the A and B elements. Induction of these factors is also a delayed response to serum stimulation and reaches a maximum 6-9 h after stimulation. Element A, which is an unusual GC-rich sequence, forms several serum-inducible DNA-protein complexes, all of which depend on contacts within GC boxes. A major inducible complex of element A contains a factor that is supershifted by antibodies against the transcription factor Sp1. The B element appears to have overlapping binding sites for two types of factors. One of these sites binds factors that are competed off by an AP-1 consensus-binding site. The other B element site binds inducible factors that interact with GC boxes, identical to those observed for element A.
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PMID:Mitogen induction of nuclear factors that interact with a delayed responsive region of the transferrin receptor gene promoter. 766 27

A set of Theiler's murine encephalomyelitis virus mutants with engineered alterations in the conserved oligopyrimidine/AUG tandem (E. V. Pilipenko, A. P. Gmyl, S. V. Maslova, G. A. Belov, A. N. Sinyakov, M. Huang, T. D. K. Brown, and V. I. Agol, J. Mol. Biol. 241:398-414, 1994) were assayed for their growth potential in BHK-21 cells (as reflected in plaque size) and for neurovirulence upon intracerebral inoculation of mice. Tandem-destroying mutations, which included substitutions in the oligopyrimidine moiety and extended insertions into the oligopyrimidine/AUG spacer, exerted relatively little effect on the plaque size but ensured a high level of attenuation. The attenuated mutants exhibited remarkable genetic stability upon growth in BHK-21 cells. However, the brains of rare animals that developed symptoms after the inoculation with high doses of these mutants invariably contained pseudorevertants with the oligopyrimidine/AUG tandem restored by diverse deletions or an AUG-generating point mutation. The AUG moiety of the tandem in the revertant genomes was represented by either a cryptic codon or initiator codon. The results demonstrate that the tandem, while dispensable for the Theiler's murine encephalomyelitis virus growth in BHK-21 cells, is essential for neurovirulence in mice. Thus, the oligopyrimidine/AUG tandem is a host-dependent cis-acting control element that may be essential for virus replication under certain conditions. The functional activity of the tandem was retained when its oligopyrimidine or AUG moieties were made double stranded. A possible role of the tandem in the cap-independent internal initiation of translation on the picornavirus RNA templates is discussed.
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PMID:Attenuation of Theiler's murine encephalomyelitis virus by modifications of the oligopyrimidine/AUG tandem, a host-dependent translational cis element. 781 54

Previous work has identified a prominent 22-24-kD protein that is present in rat male reproductive tissues, including epididymis and testis (Brooks, 1985; Jones and Brown, 1987; Moore et al., 1987). Using a monoclonal antibody (designated mAb-B109) against this 24-kD antigen (referred to as B109), we have isolated the protein using a combination of chromatofocusing and electroelution from SDS-PAGE gels, and reverse phase HPLC. B109 (pI = 4.8) is amino-terminal blocked. To obtain internal amino acid sequences, the isolated protein was cleaved either with cyanogen bromide in 70% formic acid or with TLCK-treated chymotrypsin. With cyanogen bromide treatment, two peptides, 17.8 kD and 11.9 kD, were isolated and partial amino acid sequences obtained. Chymotryptic peptides were isolated by reverse-phase HPLC and two were chosen for sequence analysis. A computer search for sequence homology through the protein identification resource (PIR) matched B109 to a basic 21-kD cytosolic protein (pI = 7.4) found in bovine brain (> 80% homology). When peptide sequence differences obtained in the present study were substituted into the 21-kD cytosolic protein sequence obtained from the PIR using Intelligenetics software, the calculated pI dropped from 7.4 to 5.8, suggesting that pI differences between the bovine and rat molecules are the result of amino acid substitutions in the testis protein and not tissue-specific posttranslational processing. It has been postulated that the 21-kD bovine brain protein is associated with phospholipid transport, although the function of B109 is unknown.
Mol Reprod Dev 1994 Nov
PMID:Putative rat sperm lipid-binding protein: isolation and partial characterization. 788 68

The yeast TRP3 gene encodes a bifunctional protein with anthranilate synthase II and indoleglycerol-phosphate synthase activities. Replacing ten consecutive non-preferred codons in the indoleglycerol-phosphate synthase region of the TRP3 gene with synonymous preferred codons (to create the TRP3pr gene; translational pause replaced) causes a 1.5-fold reduction in relative indoleglycerol-phosphate synthase activity [Crombie, T., Swaffield, J.C. & Brown, A.J.P. (1992) J. Mol. Biol. 228, 7-12]. Here, we report that both the anthranilate synthase II and indoleglycerol-phosphate synthase domains are affected to similar extents when the translational pause is removed. Also, structural modelling of the yeast indoleglycerol-phosphate synthase domain against the X-ray crystal structure of indoleglycerol-phosphate synthase from Escherichia coli indicates that the translational pause lies in a region of structural divergence between similar structures. To probe the role of cytoplasmic heat-shock protein 70 (Hsp 70) chaperones in Trp3 protein folding, anthranilate synthase and indoleglycerol-phosphate synthase activities were measured in ssa and ssb mutants. Neither indoleglycerol-phosphate synthase nor anthranilate synthase were affected significantly in the ssb mutant. However, depletion of Hsp70 proteins encoded by the SSA genes led to decreased anthranilate synthase and indoleglycerol-phosphate synthase activities from the TRP3 gene, suggesting that both domains depend to some extent upon the SSA chaperone family. The data are consistent with roles for both the translational pause and Ssa chaperones in Trp3 protein folding in vivo.
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PMID:The folding of the bifunctional TRP3 protein in yeast is influenced by a translational pause which lies in a region of structural divergence with Escherichia coli indoleglycerol-phosphate synthase. 800 82

This paper continues an examination of the hypothesis that modern proteins evolved from random heteropeptide sequences. In support of the hypothesis, White and Jacobs (1993, J Mol Evol 36:79-95) have shown that any sequence chosen randomly from a large collection of nonhomologous proteins has a 90% or better chance of having a lengthwise distribution of amino acids that is indistinguishable from the random expectation regardless of amino acid type. The goal of the present study was to investigate the possibility that the random-origin hypothesis could explain the lengths of modern protein sequences without invoking specific mechanisms such as gene duplication or exon splicing. The sets of sequences examined were taken from the 1989 PIR database and consisted of 1,792 "super-family" proteins selected to have little sequence identity, 623 E. coli sequences, and 398 human sequences. The length distributions of the proteins could be described with high significance by either of two closely related probability density functions: The gamma distribution with parameter 2 or the distribution for the sum of two exponential random independent variables. A simple theory for the distributions was developed which assumes that (1) protoprotein sequences had exponentially distributed random independent lengths, (2) the length dependence of protein stability determined which of these protoproteins could fold into compact primitive proteins and thereby attain the potential for biochemical activity, (3) the useful protein sequences were preserved by the primitive genome, and (4) the resulting distribution of sequence lengths is reflected by modern proteins. The theory successfully predicts the two observed distributions which can be distinguished by the functional form of the dependence of protein stability on length. The theory leads to three interesting conclusions. First, it predicts that a tetra-nucleotide was the signal for primitive translation termination. This prediction is entirely consistent with the observations of Brown et al. (1990a,b, Nucleic Acids Res 18:2079-2086 and 18: 6339-6345) which show that tetra-nucleotides (stop codon plus following nucleotide) are the actual signals for termination of translation in both prokaryotes and eukaryotes. Second, the strong dependence of statistical length distributions on sequence-termination signaling codes implies that the evolution of stop codons and translation-termination processes was as important as gene splicing in early evolution. Third, because the theory is based upon a simple no-exon stochastic model, it provides a plausible alternative to a limited universe of exons from which all proteins evolved by gene duplication and exon splicing (Dorit et al. 1990, Science 250:1377-1382).
J Mol Evol 1994 Apr
PMID:The evolution of proteins from random amino acid sequences: II. Evidence from the statistical distributions of the lengths of modern protein sequences. 800 6

We have mutated two regions within the yeast profilin gene in an effort to functionally dissect the roles of actin and phosphatidylinositol 4,5-bisphosphate (PIP2) binding in profilin function. A series of truncations was carried out at the C terminus of profilin, a region that has been implicated in actin binding. Removal of the last three amino acids nearly eliminated the ability of profilin to bind polyproline in vitro but had no dramatic in vivo effects. Thus, the extreme C terminus is implicated in polyproline binding, but the physiological relevance of this interaction is called into question. More extensive truncation, of up to eight amino acids, had in vivo effects of increasing severity and resulted in changes in conformation and expression level of the mutant profilins. However, the ability of these mutants to bind actin in vitro was not eliminated, suggesting that this region cannot be solely responsible for actin binding. We also mutagenized a region of profilin that we hypothesized might be involved in PIP2 binding. Alteration of basic amino acids in this region produced mutant profilins that functioned well in vivo. Many of these mutants, however, were unable to suppress the loss of adenylate cyclase-associated protein (Cap/Srv2p [A. Vojtek, B. Haarer, J. Field, J. Gerst, T. D. Pollard, S. S. Brown, and M. Wigler, Cell 66:497-505, 1991]), indicating that a defect could be demonstrated in vivo. In vitro assays demonstrated that the inability to suppress loss of Cap/Srv2p correlated with a defect in the interaction with actin, independently of whether PIP2 binding was reduced. Since our earlier studies of Acanthamoeba profilins suggested the importance of PIP2 binding for suppression, we conclude that both activities are implicated and that an interplay between PIP2 binding and actin binding may be important for profilin function.
Mol Cell Biol 1993 Dec
PMID:Mutational analysis of yeast profilin. 824 1

Azo dyes, the largest portion of manufactured dyestuffs, are primarily used as colouring substances in food, textiles, and the plastic industry. It has been estimated that 128 tonnes per annum of dyes are released into the environment worldwide [Anliker, 1977]. Certain azo compounds are known to be mutagenic in bacterial tests [Yahagi et al., 1975; Venitt and Bushell, 1976; Brown et al., 1978]. Watersoluble dyes are biotransformed by intestinal micro-organisms in the gastro intestinal tract, and the toxicity, mutagenicity, and carcinogenicity of these dyes in the gut or liver may be attributed to their metabolites. Since it is desirable to have a genotoxic evaluation of a chemical being released into the environment in order to check their indiscriminate use, a project has been initiated to determine the mutagenicity of the azo dyes being used commercially. The present report deals with the results of 13 dyes tested in Salmonella typhimurium with and without metabolic activation.
Environ Mol Mutagen 1993
PMID:Screening of azo dyes for mutagenicity with Ames/Salmonella assay. 840 79

A NMR method based on the analysis of the transverse magnetization decay curve of water protons, was employed to study the hydration process of Ife Brown cowpeas. In order to investigate the role of pH and Ionic Strength (IS) on the hydration process the beans were soaked in solutions at different IS and at different pH-constant IS. The kinetic constant for the hydration process and the water-holding capacity of the seeds in different conditions were measured.
Cell Mol Biol (Noisy-le-grand) 1993 Mar
PMID:NMR study of seed hydration: effect of pH and ionic strength on water uptake of soaked cowpeas. 851 74

The polymorphic epithelial mucin, PAS-I (also known as MUC1), in individual milk samples from 119 Holstein cows was resolved into bands on SDS-gels. Mobility indices established for these bands provided evidence of four and possibly five polymorphic forms. Sialic acid, a major component of the oligosaccharide portion of PAS-I, was removed from the mucin by treatment of milk samples with neurominidase. This reduced the mobility of the mucin bands but did not alter their mobility relationships within a sample or among samples. Consideration of evidence from this and other studies indicates that the four or five polymorphic forms correspond to alleles, which are inherited, one each from sire and dam, and co-dominantly expressed. It appears that the Holstein population may carry several more alleles for PAS-I than do Ayrshire, Jersey or Brown Swiss cattle. In addition to these breed differences, some remarkable molecular differences have been noted between MUC1 (PAS-I) of human and mouse suggesting that research regarding molecular evolution of this mucin could provide another approach to understanding relationships among species.
Comp Biochem Physiol B Biochem Mol Biol 1995 Aug
PMID:Polymorphic forms of the epithelial mucin, PAS-I (MUC1), in milk of Holstein cows (Bos taurus). 857 21

To evaluate the airway infiltration of eosinophils in the asthmatic responses of Brown-Norway rats, which were sensitized with ovalbumin, the time course of eosinophil infiltration and respiratory resistance (Rrs) after ovalbumin challenge was measured. The effect of treatment with monoclonal antibody against ICAM-1 and CD18 was studied. Finally, the expression of ICAM-1 and CD18 in the airway was investigated. All rats showed Rrs increase 6-7 hours after ovalbumin challenge, indicating a late asthmatic response (LAR). Animals with LAR had higher eosinophil counts than those with an immediate asthmatic response (IAR) and in the sensitized but nonchallenged animals. Rats treated with the antibodies showed significantly smaller increases in Rrs and lower eosinophil counts than the control animals. Immunohistochemical staining in airway was performed. ICAM-1 immunoreactivity was positive on both the epithelium and the vascular endothelium of a trachea section, and on the pulmonary vascular endothelium. ICAM-1 expression was upregulated after challenge. The number of CD18-positive cells in sections of trachea and lung increased after challenge. Our results show that eosinophil infiltration is important in LAR development and the treatment with antagonists of ICAM-1 and CD18 may provide a therapeutic approach to reducing asthmatic symptoms.
Res Commun Mol Pathol Pharmacol 1995 Oct
PMID:Role of eosinophils and cell adhesion molecules in the allergen-induced asthmatic response of rats. 858 46


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