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71.
A physical map of the human salivary proline-rich protein gene cluster covers over 700 kbp of DNA 总被引:5,自引:0,他引:5
By using a linking library, we have experimentally linked, ordered, and spaced four of the six loci that constitute the human salivary proline-rich protein (PRP) multigene family. The methods used for mapping these four PRP genes may be useful in other multigene systems in which no probes unique to each member of genes are available, but in which some enzyme site that occurs only once in each member of the family can be found. The remaining two PRP loci have been provisionally mapped and linked within the gene cluster primarily on the basis of the resulting order giving a simple map. The order of the six loci that most simply accounts for our data is PRB2, PRB1, PRB4, PRH2, PRB3, and PRH1. The PRP gene cluster spans at least 700 kbp on chromosome 12 at p13.2. A scheme for the evolution of the cluster that requires an initial gene duplication followed by three unequal but homologous crossovers is given. 相似文献
72.
Transforming growth factor-beta: multifunctional regulator of differentiation and development 总被引:8,自引:0,他引:8
A B Roberts K C Flanders U I Heine S Jakowlew P Kondaiah S J Kim M B Sporn 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1990,327(1239):145-154
Transforming growth factors-beta (TGF-beta) are 25 kilodalton (kDa) homodimeric peptides with multifunctional actions controlling the growth, differentiation and function of a broad range of target cells of both epithelial and mesenchymal derivation. They are expressed early in embryogenesis and their tissue-specific and developmentally dependent expression is strongly suggestive of an essential role in particular morphogenetic and histogenetic events. Five distinct TGF-beta s have been characterized so far, with 65-80% homology to each other. By using both molecular biological and immunohistochemical techniques, we are currently attempting to define specific sites of expression of the different TGF-beta s and to determine whether TGF-beta s 1-5 might have unique functions in development and in the mature organism. Comparative study of the promoter regions for the different TGF-beta s and for any particular TGF-beta in different species is also underway. Mechanistically, TGF-beta s act to control gene expression of their target cells, many of their actions converging on a complex, multifaceted scheme of control of matrix proteins and their interactions with cells; these effects on matrix are thought to mediate many of the effects of TGF-beta on development. 相似文献
73.
Purification of multiple erythroid cell proteins that bind the promoter of the alpha-globin gene. 总被引:9,自引:6,他引:3 下载免费PDF全文
Three erythroid cell factors that bind the murine alpha-globin promoter were enriched more than 1,000-fold by conventional and DNA sequence affinity chromatography. Visualization of enriched polypeptides revealed simple patterns suggesting that each binding activity was purified. Two of the purified proteins, alpha-CP1 and alpha-CP2, have been shown previously to interact with distinct binding sites that overlap in the alpha-globin CCAAT box. Affinity purification of alpha-CP1 revealed seven polypeptides with Mrs raging from 27,000 to 38,000. In contrast, purified alpha-CP2 was made up of a polypeptide doublet with Mrs of 64,000 and 66,000. The third purified binding activity, alpha-IRP, interacted with sequences that formed an inverted repeat (IR) between the alpha-globin CCAAT and TATAA boxes. Affinity-purified alpha-IRP was made up of a single polypeptide with an Mr of 85,000. We confirmed that the purified polypeptides corresponded to alpha-CP1-, alpha-CP2-, and alpha-IRP-binding activities by UV cross-linking experiments (alpha-CP2 and alpha-IRP) or by renaturation of binding activity after elution of polypeptides from sodium dodecyl sulfate-polyacrylamide gels (alpha-CP1 and alpha-CP2). The apparent complexity of the polypeptides accounting for alpha-CP1 binding activity prompted a further physical characterization of this factor. Sedimentation of affinity-purified alpha-CP1 in glycerol gradients containing 100 mM KCl showed that all seven polypeptides migrated as a complex that cosedimented with alpha-CP1-binding activity. In contrast, when sedimented in glycerol gradients containing 500 mM KCl, alpha-CP1 dissociated into at least two components. Under these conditions, alpha-CP1-binding activity was reduced or lost. Activity was reconstituted, however, by combining fractions that were enriched in the two components. These results were confirmed by experiments in which we showed that alpha-CP1-binding activity can be recovered only by combining distinct sets of polypeptides that were isolated and renatured from sodium dodecyl sulfate-polyacrylamide gels. Our results suggest that the seven polypeptides visualized after affinity purification of alpha-CP1 interact to form a heterotypic complex (or set of complexes) required for alpha-CP1-binding activity. 相似文献
74.
Evangelia G. Kranias Ramesh C. Gupta Gyorgyi Jakab Hae Won Kim Nancy A. E. Steenaart Stephen T. Rapundalo 《Molecular and cellular biochemistry》1988,82(1-2):37-44
Summary Canine cardiac sarcoplasmic reticulum is phosphorylated by adenosine 3,5-monophosphate (cAMP)-dependent and by calcium · calmodulin-dependent protein kinases on a 27 000 proteolipid, called phospholamban. Both types of phosphorylation are associated with an increase in the initial rates of Ca2+ transport by SR vesicles which reflects an increased turnover of elementary steps of the calcium ATPase reaction sequence. The stimulatory effects of the protein kinases on the calcium pump may be reversed by an endogenous protein phosphatase, which can dephosphorylate both the CAMP-dependent and the calcium · calmodulin-dependent sites on phospholamban. Thus, the calcium pump in cardiac sarcoplasmic reticulum appears to be under reversible regulation mediated by protein kinases and protein phosphatases. 相似文献
75.
Search for the optimal sequence of the ribosome binding site by random oligonucleotide-directed mutagenesis. 总被引:5,自引:2,他引:3 下载免费PDF全文
Synthetic DNA duplexes corresponding to the ribosome binding site (RBS) were synthesized through the phosphite method on solid support. The synthetic RBS DNA with partial random sequences was inserted into an appropriate site between the lpp-lac promoter and the beta-galactosidase structural gene in plasmid pMKT2. The level of beta-galactosidase expression was correlated with the color intensity of the recombinant colonies on X-gal plates. The bluest colonies were isolated and characterized with respect to beta-galactosidase enzyme activity and RBS sequence. There was good correlation between color intensity and the level of the enzyme activity, and this provided a reliable phenotypic screening method in the search for the optimal regulatory sequences. Novel RBS sequences obtained here show not only the unique nucleotide distribution, but also strong complemetarity to the 3' end region of 16S rRNA, from which could be deduced a generalized RBS sequence, the position of the SD region, and the 16S rRNA position mediated during translation initiation. 相似文献
76.
77.
Chronic amphetamine alters D-2 but not D-1 agonist-induced behavioral responses in rats 总被引:2,自引:0,他引:2
In two experiments, using different drug doses and periods of drug administration, rats were given amphetamine (AMPH) either continuously (via slow-release pellets), or intermittently (via injections). In both experiments, only the rats pretreated with intermittent AMPH subsequently showed heightened responsivity to the selective D-2 dopamine agonist LY171555 but not to SKF38393 (a D-1 agonist). This altered response to LY171555 was still present 30 days after the AMPH withdrawal, implying that D-2 dopamine receptors at least partially mediate AMPH inverse tolerance effects. The behavioral response to the D-2 agonist was clearly different in animals receiving high versus low doses of AMPH, suggesting that different drug-state learning may have occurred during pretreatment. In a third experiment, in which rats were given repeated daily injections of either the D-1 or the D-2 agonist, only rats pretreated with the D-2 agonist and subsequently injected with the D-2 agonist clearly showed heightened responsivity. These data imply an important role of D-2 receptors in the AMPH inverse tolerance effect. 相似文献
78.
Production and Characterization of Monoclonal Antibodies to Wall-Localized Peroxidases from Corn Seedlings 总被引:2,自引:1,他引:1 下载免费PDF全文
Sung-Ha Kim Maurice E. Terry Pepper Hoops Marianne Dauwalder Stanley J. Roux 《Plant physiology》1988,88(4):1446-1453
A library of 22 hybridomas, which make antibodies to soluble wall antigens from the coleoptiles and primary leaves of etiolated corn (Zea mays L.) seedlings, was raised and cloned three times by limit dilution to assure monoclonal growth and stability. Two of these hybridomas made immunoglobulin G antibodies, designated mWP3 and mWP19, which both effectively immunoprecipitated peroxidase activity from crude and partially purified preparations of wall peroxidases. Direct peroxidase-binding assays revealed that both antibodies bound enzymes with peroxidase activity. As judged by immunoblot analyses, mWP3 recognized a Mr 98,000 wall peroxidase with an isoelectric point near 4.2, and mWP19 recognized a Mr 58,000 wall peroxidase. Immunogold localization studies showed both peroxidases are predominately in cell walls. 相似文献
79.
Physical interactions between pyridoxal kinase and aspartate aminotransferase were detected by means of emission anisotropy and affinity chromatography techniques. Binding of aspartate aminotransferase (apoenzymes) to pyridoxal kinase tagged with a fluorescent probe was detected by emission anisotropy measurements at pH 6.8 (150 mM KCl). Upon saturation of the kinase with the aminotransferase, the emission anisotropy increases 22%. The protein complex is characterized by a dissociation constant of 3 microM. Time-dependent emission anisotropy measurements conducted with the mixture 5-naphthylamine-1-sulfonic acid-kinase aspartate aminotransferase (apoenzyme), revealed the presence of two rotational correlation times of phi 1 = 36 and phi 2 = 62 ns. The longer correlation time is attributed to the stable protein complex. By immobilizing one enzyme (pyridoxal kinase) through interactions with pyridoxal-Sepharose, it was possible to demonstrate that aspartate aminotransferase releases pyridoxal kinase. A test of compartmentation of pyridoxal-5-phosphate within the protein complex using alkaline phosphatase as trapping agent, indicates that the cofactor generated by the catalytic action of the kinase is channeled to the apotransaminase. The main function of the stable complex formed by the kinase and the aminotransferase is to hinder the release of free pyridoxal-5-phosphate into the bulk solvent. 相似文献
80.
Ubiquitin genes in trypanosomatidae 总被引:11,自引:0,他引:11
L V Kirchhoff K S Kim D M Engman J E Donelson 《The Journal of biological chemistry》1988,263(25):12698-12704