Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

E. coli SK has its own enzyme system providing DNA host specificity which differs from the known types of specificity in E. coli K12 and E. coli B. Modification and restriction are observed when the PBVI or PBV3 phages are transferred from E. coli SK to E. coli B or K12 (and back). A methylase has been isolated from E. coli SK cells and partly purified. This methylase catalyzes in vitro transfer of the labelled methyl groups from S-adenosylmethionine (SAM) to DNA of both phage and tissue origin which gives rise to 5'-methylcytosine (5'MC) and 6'-methylaminopurine (6'MAP). The methylase preparations isolated from the cells at the stationary growth have proved to be 1.5-1.7 times as active as the enzyme from the cells at the logarithmic growth stage. The extract of E. coli SK cells infected with the phage SD cannot methylate DNA in vitro. This fact is due to de novo synthesis of the enzyme which disintegrates SAM down to 5'-methyltioadenosine (5'MTA) and homoserine (HS). This enzyme is not found in the cells infected with the SD phage in the presence of chloroamphenicole. The activity of the enzyme which disintegrates SAM is the highest between the 4th and the 5th minutes of infection. Thus it may be assumed that this enzyme, most probably, is an early virus specific protein and prevents in vivo methylation of the phage DNA.
Mol Cell Biochem 1976 Nov 30
PMID:The host specificity system in Escherichia coli SK. 79 97

Expression of the mouse beta-PDGF receptor by gene transfer confers PDGF-dependent and reversible neuronal differentiation of PC12 pheochromocytoma cells similar to that observed in response to NGF and basic FGF. A common property of the PDGF, NGF, and basic FGF-induced differentiation response is the requirement for constant exposure of cells to the growth factor. To test the hypothesis that a persistent level of growth factor receptor signaling is required for the maintenance of the neuronal phenotype, we examined the regulation of the serine/threonine-specific MAP kinases after either short- (10 min) or long-term (24 h) stimulation with growth factors. Mono Q FPLC resolved two peaks of growth factor-stimulated MAP kinase activity that coeluted with tyrosine phosphorylated 41- and 43-kDa polypeptides. MAP kinase activity was markedly stimulated (approximately 30-fold) within 5 min of exposure to several growth factors (PDGF, NGF, basic FGF, EGF, and IGF-I), but was persistently maintained at 10-fold above basal activity after 24 h only by the growth factors that also induce PC12 cell differentiation (PDGF, NGF, and basic FGF). Thus the beta-PDGF receptor is in a subset of tyrosine kinase-encoded growth factor receptors that are capable of maintaining continuous signals required for differentiation of PC12 cells. These signals include the constitutive activation of cytoplasmic serine/threonine protein kinases.
Mol Biol Cell 1992 May
PMID:The beta-PDGF receptor induces neuronal differentiation of PC12 cells. 131 43

The proto-oncogene c-Kit, a transmembrane receptor tyrosine kinase, is an important regulator of cell growth whose constitutively active oncogenic counterpart, v-kit, induces sarcomas in cats. Mutations in murine c-kit that reduce the receptor tyrosine kinase activity cause deficiencies in the migration and proliferation of melanoblasts, hematopoietic stem cells, and primordial germ cells. We therefore investigated whether c-Kit regulates normal human melanocyte proliferation and plays a role in melanomas. We show that normal human melanocytes respond to mast cell growth factor (MGF), the Kit-ligand that stimulates phosphorylation of tyrosyl residues in c-Kit and induces sequential phosphorylation of tyrosyl residues in several other proteins. One of the phosphorylated intermediates in the signal transduction pathway was identified as an early response kinase (mitogen-activated protein [MAP] kinase). Dephosphorylation of a prominent 180-kDa protein suggests that MGF also activates a phosphotyrosine phosphatase. In contrast, MGF did not induce proliferation, the cascade of protein phosphorylations, or MAP kinase activation in the majority of cells cultured from primary nodular and metastatic melanomas that grow independently of exogenous factors. In the five out of eight human melanoma lines expressing c-kit mRNAs, c-Kit was not constitutively activated. Therefore, although c-Kit-kinase is a potent growth regulator of normal human melanocytes, its activity is not positively associated with malignant transformation.
Mol Biol Cell 1992 Feb
PMID:c-Kit-kinase induces a cascade of protein tyrosine phosphorylation in normal human melanocytes in response to mast cell growth factor and stimulates mitogen-activated protein kinase but is down-regulated in melanomas. 137 24

The microtubule-associated protein Tau, a major component of brain microtubules, shares common repeated C-terminal sequences with the high molecular-weight protein MAP-2. It has been shown that tau peptides V187-G204 and V218-G235, representing two main repeats, induced brain tubulin assembly in a concentration-dependent fashion. The specific roles of these repeats in the interaction of tau with microtubules, and its antigenic nature were investigated using synthetic tau peptides and site-directed monoclonal antibodies. Tau peptides appeared to compete with MAP-2 incorporation into assembled microtubules. The interactions of the tau fragments with beta-tubulin peptides bearing the tau binding domain on tubulin were analyzed by fluorescence spectroscopy. The specificity of the binding was further demonstrated by the reactivity of tau and the tau peptides with a monoclonal anti-idiotypic antibody produced after immunization with the beta-II(422-434) tubulin peptide, as assessed by enzyme-linked immunoassay. Western blots confirmed the interaction of tau with the monoclonal antibody. In addition, immunoassays revealed a competition between the MAP-reacting monoclonal antibody and the tubulin peptide beta-II(422-434) for their interaction with the tau molecule.
Mol Cell Biochem 1992 May 13
PMID:Specific macromolecular interactions between tau and the microtubule system. 151 37

The aim of this study was to compare the antigenicity and the immunogenicity of five constructs of a peptide, including the peptide in single copy, a tandem repeat containing three copies, a copolymer with glutaraldehyde and two constructs based on the MAP (Multiple Antigenic Peptide) model, one containing two copies (MAP-2) and the other, eight copies of the peptide (MAP-8). The peptide used in this test was the 115-131 sequence derived from the rSm28-GST antigen of Schistosoma mansoni. All constructs were recognized by rSm28-GST specific antibodies in solid phase immunoassays. However, the binding was higher when the MAP-8 was used as antigen at least partly because of its better coating on the microtiter plates. In vitro lymphoproliferative assays showed that polymer was mitogenic, repeat and MAP-2 did not stimulate rSm28-GST specific T cells while MAP-8 induced a slight response. The injection of MAP-8 to rats led to important antibody and T cell responses higher than those obtained with the other constructs. The IgG2a (cytotoxic antibody in schistosomiasis)/IgG2c (blocking antibody) ratio was independent of the immunogen. Taken together these results demonstrate that both the antigenicity and the immunogenicity of a peptide containing T and B cell epitope(s) are strongly related to the molecular form whereby it is presented and that the MAP-8 construct can be useful in serodiagnosis or in vaccination trials using synthetic peptides.
Mol Immunol 1992 Jun
PMID:Analysis of antigenicity and immunogenicity of five different chemically defined constructs of a peptide. 160 96

We have isolated the MAP/tau proteins from twice-cycled chick brain microtubule preparations and demonstrated that they are responsible for the nitrocellulose DNA binding activity we and others have measured. Using the isolated MAP/tau proteins we then measured the apparent affinity constant K(app) for the homologous chick DNA interaction and found evidence for two equilibrium affinity classes-a K(app) = 6 x 10(7) M-1, responsible for the bulk of the DNA binding activity and a small (less than 10%) higher affinity K(app) = 10(8) - 10(9) M-1, likely due to sequence specific binding protein species. Using the same chick brain MAP-tau protein, a heterologous interaction with D. melanogaster DNA, was found to possess just the lower affinity class-K(app) = 2 x 10(7) M-1. Under stringent binding conditions we carried out equilibrium nitrocellulose filter binding experiments in a ternary reaction mixture at constant MAP/tau protein and 35S radiolabelled chick DNA concentration using increasing and excess concentrations of competitor DNAs of different sources. The order of competitor strengths found was-chick DNA greater than mouse DNA greater than D. melanogaster = E. coli. DNA. These data and specifically the homologous DNA: protein case being the strongest competitor corroborate our previous studies using total microtubule protein and provide new evidence for a conserved interaction of a small DNA sequence class with MAP/tau protein species. Moreover, these data allow us to conclude that the conserved DNA sequence: MAP/tau protein interactions do not critically depend upon any energetic feature co-involving tubulin for their properties since tubulin is absent from these preparations.
Mol Cell Biochem 1992 Jul 06
PMID:High affinity DNA-microtubule associated protein interaction. 164 Sep 36

Antibodies were elicited against a synthetic peptide which encompassed two different regions of the human lutropin beta-subunit (hLH-beta). These antibodies were raised against either the peptide which was assembled using a conventional approach and conjugated to the tetanus toxoid, or with the peptide assembled using the multiple antigen peptide system approach. Automated simultaneous synthesis of the two forms of the immunizing peptide was successfully achieved. Animal injected with the peptide conjugated to tetanus toxoid produced high titers of antibodies to the synthetic peptide, but did not bind to the native hLH-beta subunit. In contrast, antisera induced by the peptide in its MAP form displayed reactivity with both the peptide and the native hLH-beta subunit; these latter antisera appeared to preferentially recognize the beta 47-55 portion of the molecule and were able to bind to the beta-subunit of human choriogonadotropin. Present results demonstrate that the beta 47-55 region is accessible to antibody binding and appears to be located at the surface of both hLH-beta and hLH. Moreover, this study confirms that the MAP approach provides a chemically unambiguous method for obtaining antibodies of predetermined specificity, capable of recognizing cognate sequences of various native proteins.
Mol Immunol 1990 Apr
PMID:Structural probing of human lutropin using antibodies raised against synthetic peptides constructed by classical and multiple antigen peptide system approaches. 169 62

In our previous study, a drastic change in terminal saccharides of glycoconjugates of the hamster zona pellucida associated with oocyte maturation was observed using light microscopic methods of lectin cytochemistry. To understand the mechanism of this change, in the present study, the correlation between the cytochemical appearance of saccharide residues in the zona pellucida and nuclear maturation was examined. Immature hamsters were treated with PMSG and hCG to induce follicular development and ovulation. The animals were euthanized 0 to 26 hrs. after the injection of PMSG or 0,1,2,3,4,5,7,9 or 11 hrs. after the injection of hCG, and ovaries were dissected out, fixed, paraffin embedded and sectioned serially. Every other paraffin section was stained with hematoxylin to observe the status of nuclei and to classify follicular growth and only the fully developed preovulatory follicles were examined in experiments. The peroxidase-labelled lectin-diaminobenzidine procedure was applied to sections. The lectins employed were WGA, SBA, MPA, UEA-I, LotusA and AAA. Germinal vesicle breakdown was observed within 3 hrs. after the administration of hCG. A positive reaction of WGA, SBA or MPA for zonae pellucidae in the fully developed preovulatory follicles appeared 1 hr. after hCG injection, and remained so for the next 10 hrs. UEA-I, Lotus A and AAA reactions were negative for all of the zonae pellucidae observed. The data indicate that the synthesis of saccharide residues such as GlcNAc and GalNAc forming zona components in the follicles is not triggered by germinal vesicle breakdown.
Cell Mol Biol 1991
PMID:Appearance of lectin binding affinity to the zona pellucida during hamster oocyte maturation. 174 97

Weight gain and psychomotor development of breastfed infants of Egyptian mothers using Norplant, Cu T-380A IUDs, norethisterone enanthate injectables (NET-EN), Depo Provera and a levonorgestrel minipill were compared in 2 trials. First, groups of 120 women using Norplant and NET-EN were compared to a control group using IUDs, beginning 5-7 weeks postpartum. There were no differences in infant weight gain, mid-arm circumference, triceps-skin-fold thickness, or timing of motor milestones. The mean growth curve of all 3 groups were close to that of the 50th percentile for Egyptian infants. While timing of initiation of supplements was similar in the 3 groups, complete weaning occurred first in the IUD group, second in the Norplant group, and last in the NET-EN users. A second trail compared progesterone implants injected with a trocar that resulted in a blood level of 3 ng/ml for 5 months, with Population Council vaginal rings releasing 10 progesterone/24 hours, and CuT-380A IUDs. Serum progesterone in the ring users averaged 5.2 ng/ml for the 1st 2 weeks, then leveled off at about 4 ng/ml for about 2 months, falling to about 3 ng/ml for the last 3 weeks of use. Each women used 4 rings per year. Evidence of ovulation by ultrasonic vaginal probe and assay of estradiol and progesterone was apparent in 25% of vaginal ring users, compared to 55.9% of controls in the 2nd 6 months postpartum. There was 1 pregnancy in a ring users. The continuation rates were 66.6% for rings and 85.5% for IUDs. The reasons for discontinuation in vaginal ring continuation were logistical problems and unfamiliarity.
J Steroid Biochem Mol Biol 1991
PMID:Contraception with progestogens and progesterone during lactation. 183 50

A survey of recent trials of new injectable hormonal contraceptives, progestogen-only, levonorgestrel esters, and once monthly injectables, follows a brief review of all the experimental long-acting contraceptive modalities, injectables, implants, vaginal rings, and hormone-releasing IUDs. Currently medroxyprogesterone acetate (DMPA) and norethisterone enanthate (NET-EN) are being used by 7 million women. WHO is conducting dose reduction trials and studies of bioavailability in various national populations. Even though a dose of 100 mg DMPA every 3 months has been satisfactory for contraception, 150 mg is still recommended until further pharmacodynamic data are available. Some populations, notably Thais and Mexican women, have higher peaks and more rapid elimination rates of DMPA, while Chinese women show slower elimination and higher blood levels of NET-EN. Extensive studies of new synthetic esters of levonorgestrel have proceeded to Phase II clinical trials with levonorgestrel butanoate. This ester is an effective contraceptive for 3 months at 12.5 mg, or 5-6 months at a dose of 25 or 50 mg. Trials of combined estrogen and progestogen injectables once-monthly have been ongoing for 10 years. The ratio of the 2 components is as important as the amounts. 2328 women from 12 countries participated in trials of DMPA 25 mg-estradiol cypionate 5 mg, and NET-EN 50 mg-estradiol valerate 5 mg. The continuation rate was better than that for 3-monthly progestogen-only injectables, because of less irregular bleeding. A combined injectable called Cyclofem, DMPA 25 mg-estradiol cypionate is being introduced in several countries. The steadily increasing demand for long-acting injectables prompts development of better formulations.
J Steroid Biochem Mol Biol 1991
PMID:Long-acting hormonal contraceptives for women. 195 67


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