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)

Actin filaments capped at the barbed ends were formed by polymerizing monomeric actin onto a gelsolin-actin complex. The rate of depolymerization and polymerization of the pointed ends was determined by diluting gelsolin-capped actin filaments into various concentrations of monomeric actin. Under the conditions of the experiments (100 mM-KCl, 2 mM-MgCl2 at 37 degrees C) the rate constant of dissociation of subunits both from a shortening and a lengthening filament was found to be 0.21 s-1. As the rate of dissociation of subunits from the slow pointed end determines the rate of treadmilling, it is concluded that actin filaments treadmill with a rate of about 2 micron/h.
J Mol Biol 1986 Feb 20
PMID:Rate of treadmilling of actin filaments in vitro. 301 95

The beta-adrenergic receptor in membranes from cat, rat, and guinea pig hearts appears to undergo spontaneous coupling to the stimulatory nucleotide-regulatory protein, Ns. This was demonstrated by incubating cardiac membranes from acutely reserpinized animals with the alkylating reagent N-ethylmaleimide (NEM), which is known to "freeze" the beta-receptor Ns-complex. The concentration of norepinephrine in these membrane preparations was less than 0.1 nM. Cat heart membranes were preincubated for 10 min at 30 degrees with NEM (10(-7)-10(-3) M) and subsequently incubated with (-)-[125I]iodopindolol (IPIN) (18 min, 30 degrees). NEM caused a concentration-dependent decrease in specific IPIN binding with a maximal reduction of about 20% at 0.1 mM. This decrease occurred even in the absence of MgCl2 (0.5 mM EDTA added as well). A comparable reduction was also observed in myocardial membranes from rat and guinea pig. This fall reflects a decrease in the number of beta-adrenergic receptor sites, as demonstrated by saturation binding experiments with IPIN. The equilibrium dissociation constant of the radioligand for the remaining receptors was not affected. When increasing concentrations of GTP were included in the preincubation mixture, it resulted in a dose-dependent protection of NEM-induced decrease in IPIN binding. The protection was complete at 0.1 mM GTP. In addition, GTP reversed the NEM effect when added to the incubation mixture 10 min after NEM. The apparent reduction in cardiac beta-adrenergic receptor number by NEM (in the absence of beta-receptor agonist) is compatible with a model in which part of the receptor population is able to undergo spontaneous coupling to Ns.
Mol Pharmacol 1986 Jul
PMID:Spontaneous coupling of the beta-adrenergic receptor to Ns in mammalian cardiac membranes. 301 6

[3H]-(+/-)-L-364,718 a new, potent and selective nonpeptide peripheral cholecystokinin (CCK) antagonist bound saturably and reversibly to rat pancreatic membranes. The radioligand recognized a single class of binding sites with a high affinity (Kd = 0.23 nM). The binding of [3H]-(+/-)-L-364,718 was stereospecific in that the more biologically active (-)-enantiomer demonstrated greater potency than the (+)-enantiomer. The rank order of potency of various CCK agonists and antagonists in displacing [3H]-(+/-)-L-364,718 correlated with their ability to displace [125I]CCK-8 and their known pharmacological activities in peripheral tissues. However, the absolute potencies of agonists were greater in displacing [125I]CCK-8 than [3H]-(+/-)-L-364,718. As described for other physiologically relevant receptor systems, the potency for displacement of [3H]-(+/-)-L-364,718 binding by CCK agonists, but not antagonists, was reduced by guanosine 5'-(beta, gamma-imido)triphosphate and NaCl and enhanced by MgCl2. [3H]-(+/-)-L-364,718 also demonstrated specific binding to bovine gall bladder tissue but not guinea pig brain or gastric glands, consistent with its selectivity as a peripheral CCK antagonist. [3H]-(+/-)-L-364,718 binding to pancreatic membranes was not affected by various pharmacological agents known to interact with other common peptide and nonpeptide receptor systems. These data indicate that [3H]-(+/-)-L-364,718 represents a new potent nonpeptide antagonist radioligand for the study of peripheral CCK receptors which may allow differentiation of agonist and antagonist interactions.
Mol Pharmacol 1986 Sep
PMID:Characterization of the binding of [3H]-(+/-)-L-364,718: a new potent, nonpeptide cholecystokinin antagonist radioligand selective for peripheral receptors. 301 78

A type I topoisomerase has been purified to near homogeneity from the trypanosomatid Crithidia fasciculata. The topoisomerase consists of a single 79 kDa polypeptide. The enzyme does not require divalent cations but is stimulated 10-20 fold by the presence of MgCl2. ATP does not affect enzyme activity, while Berenil, N-ethylmaleimide and ethidium bromide are inhibitory. Immunoblots show that the 79 kDa polypeptide is the most prevalent form of the enzyme in extracts of freshly lysed cells and is immunogenically conserved among a variety of trypanosomes. The topoisomerase was localized to the cell nucleus by double antibody immunofluorescence.
Mol Biochem Parasitol 1987 Jun
PMID:Purification and nuclear localization of a type I topoisomerase from Crithidia fasciculata. 304 Dec 12

The functional activity of the wide-spread "tight" 70S ribosomes is usually equal to 55-80%. We show here that the inactive fraction of this type of ribosomes is virtually blocked by residual endogenous RNA's. These RNA's are shown to be removable by introducing an additional stage in the isolation procedure including: 1. short heating (15 min, 37 degrees C) of "tight" 70S under dissociation conditions, i. e. in a buffer containing 3 mM MgCl2 and 200 mM NH4Cl; 2. washing off endogenous RNA's on a sucrose density gradient in the same buffer; 3. final selection of purified "tight" 70S on the sucrose gradient containing 5 mM MgCl2 and 50 mM NH4Cl. "Tight" 70S ribosomes isolated by such a procedure are 90-100% active with respect to tRNA binding (including the factor-dependent one), peptide bond synthesis and translocation.
Mol Biol (Mosk)
PMID:[A modified method of isolation of "tight" 70S ribosomes from Escherichia coli highly active at different stages of the elongation cycle]. 305 95

Light scattering, sedimentation and electron microscopy have been used to investigate the aggregation states of highly purified RecA protein in solution. We show that RecA protein will self-assemble into a discrete series of quaternary structures depending upon protein concentration, ionic environment, and nucleotide cofactors. In a stock solution at moderate concentration (10 to 50 microM) RecA protein exists as small particles approximately 4 nm in diameter, larger particles approximately 12 nm in diameter (most probably rings of RecA protein), 10 nm diameter rods varying from 50 to 200 nm in length, and finally as much larger bundles of rods. The addition of monovalent salt shifts the distribution of RecA protein between its various oligomeric states. Increasing protein concentration favors more highly aggregated structures. At a given protein concentration, addition of mM levels of MgCl2 promotes the rapid formation of rods and slow formation of bundles. Under conditions typical of in vitro strand exchange reactions, RecA protein was found to exist as a mixture of rods and 12 nm particles with relatively few monomers.
J Mol Biol 1988 Dec 20
PMID:RecA protein self-assembly. Multiple discrete aggregation states. 306 21

We have isolated a highly enriched preparation of the multienzyme complex which synthesizes deoxyribonucleoside triphosphates (dNTPs) from bacteriophage T4-infected bacteria. By a combination of SDS polyacrylamide gel electrophoresis and assays for specific enzyme activities, we have been able to identify in our final preparation ten different gene products which were previously identified as constituents of this complex, based upon studies with crude preparations. The complex dissociates at high concentrations of NaCl and MgCl2 but is stable under ionic conditions thought to exist in vivo. The purified complex catalyzes the efficient five-step conversion of dCTP to dTTP. Experiments with several T4 mutants have demonstrated that gene products encoded by cd, regA, nrdA, and nrdB are necessary to retain physical integrity of the complex throughout the preparative procedure, while gp44, gp55, and gppseT are not required. We conclude from this evidence that the T4 early gene products which function in dNTP biosynthesis are, in fact, physically linked as a multienzyme complex, and that regA contributes to the integrity of this complex. However, the dNTP-synthesizing complex as we isolate it contains no detectable DNA polymerase, nor have other known replication proteins been detected.
J Mol Recognit 1988 Feb
PMID:T4 phage deoxyribonucleoside triphosphate synthetase: purification of an enzyme complex and identification of gene products required for integrity. 307 39

A UDP-glucuronosyltransferase (UDPGT) isoenzyme capable of morphine glucuronidation has been purified to apparent homogeneity and partially characterized from hepatic microsomes of female Wistar rats which have low 3 alpha-hydroxysteroid UDPGT. A rapid and sensitive assay was developed to quantify morphine glucuronide formation using 14C-UDP-glucuronic acid and reverse phase C-18 minicolumns whereby radioactive glucuronides were differentially eluted from 14C-UDP-glucuronic acid. Trisacryl-DEAE and chromatofocusing chromatographic procedures were employed to separate and purify morphine UDPGT in the presence of exogenous phosphatidylcholine. The addition of phospholipid was necessary to stabilize UDPGT activities throughout the purification procedures. Morphine UDPGT was isolated to apparent homogeneity and displayed a pl of 7.9 upon chromatofocusing. A monomeric molecular weight of 56,000 was obtained. The purified enzyme reacted with morphine but not with 4-hydroxybiphenyl, p-nitrophenol, testosterone, androsterone, estrone, bilirubin, 4-aminobiphenyl, or alpha-naphthylamine. The MgCl2 requirement for maximal expression of morphine glucuronidation was higher for the purified enzyme than for solubilized and intact microsomes. Codeine competitively inhibits morphine glucuronidation with an apparent Ki of 1.1 mM with the purified morphine UDPGT. 4-Hydroxybiphenyl UDPGT was separated from morphine UDPGT using a chromatofocusing procedure for Emulgen 911-solubilized microsomes. An apparent pl value of 5.5 was obtained for this protein. Based on this work we conclude that morphine and 4-hydroxybiphenyl can react with separate UDPGT isoforms.
Mol Pharmacol 1986 Dec
PMID:Isolation and purification of rat liver morphine UDP-glucuronosyltransferase. 309

Factors affecting the efficiency of transfection of Ps. aeruginosa PAO1 cells by the temperate SM bacteriophage DNA have been determined. The efficiency of transfection by DNA preparations isolated from the wild type bacteriophage SMc+ or its thermoinducible mutant SM cts6 is practically the same. The frequency of transfection is (7-9) X 10(4) of infectious centers per mkg of transfecting DNA. Variability in the frequencies of transfection has been registered depending of the infection conditions or on the transfer of the Ps. aeruginosa PAO1 recipient strain population into the competence phase. The efficiency of transfection is increased by the addition of Ca2+ or Mg2+ ions affecting the adsorption and absorbtion of phage DNA by the recipient cells. Optimal concentrations of the bivalent metal ions are 0.15M CaCl2 and 0.2M MgCl2. The results obtained have been used for optimizing the conditions of Ps. aeruginosa PAO1 transfection by SM bacteriophage DNA.
Mol Gen Mikrobiol Virusol 1987 Jan
PMID:[Transfecting activity of Pseudomonas aeruginosa bacteriophage SM]. 310 74

There are one or more proteins of 50,000 to 60,000 Mr in the thin filaments of insect flight muscle. A protein of 55,000 Mr has been isolated from insect fibrillar flight muscle and called arthrin. Despite its higher molecular weight, arthrin is in many ways like actin. The amino acid composition of arthrin was similar to that of actin. There were similarities in the peptides produced by digesting the denatured proteins and mild digestion of polymerized proteins cleaved similar-sized fragments from arthrin and actin. Polymerized arthrin activated the Mg2+ ATPase of myosin to the same extent as actin and the ATPase was regulated by rabbit or Lethocerus troponin and tropomyosin. Arthrin did not itself act as troponin-T. Electron microscopy of negatively stained specimens showed that arthrin and actin filaments were similar in structure and that arthrin could be decorated by rabbit subfragment-1 to form normal-looking arrowheads. Arthrin formed paracrystals at an optimum concentration of MgCl2 (25 mM) that was somewhat lower than the optimum for actin paracrystals. Optical diffraction showed that the structure of the paracrystals was similar to those formed from actin. The mass of arthrin and actin filaments relative to phage fd was measured by scanning transmission electron microscopy; the relative mass of arthrin and actin was 1.33, in agreement with molecular weight estimations. Therefore arthrin has the properties of a heavy form of actin. The proportion of actin, arthrin and troponin-T in Lethocerus myofibrils was six moles of actin to one mole of arthrin and one mole of troponin-T. The function of arthrin is not known.
J Mol Biol 1985 Apr 05
PMID:Arthrin: a new actin-like protein in insect flight muscle. 315 2


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