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1.
Science ; 234(4774): 355-8, 1986 Oct 17.
Artículo en Inglés | MEDLINE | ID: mdl-2429366

RESUMEN

Human interferon stimulates a transient two- to threefold increase in the concentration of diacylglycerol and inositol tris-phosphate within 15 to 30 seconds of cell exposure to interferon. Antibodies to interferon inhibit this effect. The stimulation was measurable in isolated cell membranes exposed to interferon. Human alpha and beta, but not gamma, interferon stimulate this increase in cells containing the appropriate interferon receptor. The effect was proportional to the number of interferon receptors. Both the diacylglycerol increase and antiviral effects induced by interferon could be correlated in terms of dose dependence. Thus, a transient diacylglycerol increase is an early event in the interferon-induced transmembrane signaling process.


Asunto(s)
Interferones/farmacología , Animales , Comunicación Celular , Membrana Celular/efectos de los fármacos , Diglicéridos/análisis , Relación Dosis-Respuesta a Droga , Fibroblastos/análisis , Fibroblastos/efectos de los fármacos , Humanos , Inositol 1,4,5-Trifosfato , Fosfatos de Inositol/análisis , Interferón Tipo I/farmacología , Interferón gamma/farmacología , Interferones/fisiología , Ratones , Receptores Inmunológicos/metabolismo , Receptores de Interferón
2.
Biochim Biophys Acta ; 945(2): 202-10, 1988 Nov 22.
Artículo en Inglés | MEDLINE | ID: mdl-2973350

RESUMEN

Two Ca2+-stimulated ATPase activities have been identified in the plasma membrane of rat parotid: (a) a (Ca2+ + Mg2+)-ATPase with high affinity for free Ca2+ (apparent Km = 208 nM, Vmax = 188 nmol/min per mg) and requiring micromolar concentration of Mg2+ and (b) a (Ca2+ or Mg2+)-ATPase with relatively low affinity for free Ca2+ (K0.5 = 23 microM) or free Mg2+ (K0.5 = 26 microM). The low-affinity (Ca2+ or Mg2+)-ATPase can be maximally stimulated by Ca2+ alone or Mg2+ alone. The high-affinity (Ca2+ + Mg2+)-ATPase exhibits sigmoidal kinetics with respect to ATP concentration with K0.5 = 0.4 mM and a Hill coefficient of 1.91. It displays low substrate specificity with respect to nucleotide triphosphates. Although trifluoperazine inhibits the activity of the high affinity (Ca2+ + Mg2+)-ATPase only slightly, it inhibits the activity of the low-affinity (Ca2+ or Mg2+)-ATPase quite potently with 22 microM trifluoperazine inhibiting the enzymic activity by 50%. Vanadate, inositol 1,4,5-trisphosphate, phosphatidylinositol 4,5-bisphosphate, Na+,K+ and ouabain had no effect on the activities of both ATPases. Calmodulin added to the plasma membranes does not stimulate the activities of both ATPases. The properties of the high-affinity (Ca2+ + Mg2+)-ATPase are distinctly different from those of the previously reported Ca2+-pump activity of the rat parotid plasma membrane.


Asunto(s)
ATPasa de Ca(2+) y Mg(2+)/metabolismo , ATPasas Transportadoras de Calcio/metabolismo , Glándula Parótida/enzimología , Adenosina Trifosfato/metabolismo , Animales , Calcio/metabolismo , Calmodulina/farmacología , Membrana Celular/enzimología , Cinética , Magnesio/fisiología , Nucleótidos/metabolismo , Ratas , Trifluoperazina/farmacología
3.
Biochim Biophys Acta ; 429(2): 461-73, 1976 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-177071

RESUMEN

The soluble supernatant fraction of bovine heart homogenates may be fractionated on a DEAE cellulose column into two cyclic nucleotide phosphodiesterases (EC 3.1.4.-):PI and PII phosphodiesterases, in the order of emergence from the column. In the presence of free Ca2+, the PI enzyme may be activated several fold by the protein activator which was discovered by Cheung((1971) J. Biol. Chem. 246, 2859-2869). The PII enzyme is refractory to this activator, and is not inhibited by the Ca2+ chelating agent, ethylene glycol bis (beta-aminoethyl ether)-N, N'-tetraacetate (EGTA). The activated activity of PI phosphodiesterase may be further stimulated by imidazole or NH+4, and inhibited by high concentrations of Mg2+. These reagents have no significant effect on either the PII enzyme or the basal activity of PI phosphodiesterase. Although both forms of phosphodiesterase can hydrolyze either cyclic AMP or cyclic GMP, they exhibit different relative affinities towards these two cyclic nucleotides. The PI enzyme appears to have much higher affinities toward cyclic GMP than cyclic AMP. Km values for cyclic AMP and cyclic GMP are respectively 1.7 and 0.33 mM for the non-activated PI phosphodiesterase; and 0.2 and 0.007 mM for the activated enzyme. Each cyclic nucleotide acts as a competitive inhibitor for the other with Ki values similar to the respective Km values. In contrast with PI phosphodiesterase, PII phosphodiesterase exhibits similar affinity toward cyclic AMP and cyclic GMP. The apparent Km values of cyclic AMP and cyclic GMP for the PII enzyme are approx. 0.05 and 0.03 mM, respectively. The kinetic plot with respect to cyclic GMP shows positive cooperativity. Each cyclic nucleotide acts as a non-competitive inhibitor for the other nucleotide. These kinetic properties of PI and PII phosphodiesterase of bovine heart are very similar to those of rat liver cyclic GMP and high Km cyclic AMP phosphodiesterases, respectively (Russel, Terasaki and Appleman, (1973) J. Biol. Chem. 248, 1334).


Asunto(s)
Miocardio/enzimología , Hidrolasas Diéster Fosfóricas/metabolismo , 3',5'-AMP Cíclico Fosfodiesterasas/aislamiento & purificación , 3',5'-AMP Cíclico Fosfodiesterasas/metabolismo , Animales , Unión Competitiva , Bovinos , AMP Cíclico/farmacología , GMP Cíclico/farmacología , Activación Enzimática/efectos de los fármacos , Imidazoles/farmacología , Isoenzimas/aislamiento & purificación , Isoenzimas/metabolismo , Cinética , Hidrolasas Diéster Fosfóricas/aislamiento & purificación
4.
Biochim Biophys Acta ; 1351(1-2): 231-8, 1997 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-9116038

RESUMEN

A cDNA clone encoding rabbit E2(32k) was obtained by library screening and PCR. The cDNA contains an open reading frame coding for 238 amino acids which shows an overall identity of 81% to human CDC34, the cell cycle-related ubiquitin-conjugating enzyme. A 50% homology to yeast CDC34 within the conserved core domain was also observed. Northern blot analysis indicated that three transcripts existed in all six rabbit tissues examined but their expression levels varied over a wide range. The putative cDNA coding region was highly expressed in Escherichia coli as a his-tagged protein which was purified to homogeneity. The ability of this expressed protein to form a thiolester bond with ubiquitin showed that it was functionally active. The ability of this protein to catalyze the conjugation of ubiquitin to histone H2A and H2B was also examined.


Asunto(s)
Ligasas/genética , Complejos de Ubiquitina-Proteína Ligasa , Ubiquitinas/metabolismo , Secuencia de Aminoácidos , Ciclosoma-Complejo Promotor de la Anafase , Animales , Secuencia de Bases , Clonación Molecular , Escherichia coli/genética , Ésteres/metabolismo , Ligasas/aislamiento & purificación , Datos de Secuencia Molecular , ARN Mensajero/aislamiento & purificación , Conejos , Proteínas Recombinantes/aislamiento & purificación , Reticulocitos/enzimología , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Compuestos de Sulfhidrilo/metabolismo , Distribución Tisular , Enzimas Ubiquitina-Conjugadoras , Ubiquitina-Proteína Ligasas
5.
Gene ; 196(1-2): 19-23, 1997 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-9322736

RESUMEN

A cDNA clone encoding ubiquitin-activating enzyme E1 has been isolated from a rabbit heart cDNA library and sequenced. The 3.485 kb cDNA contains an open reading frame of 1058 amino acid residues which predicts a protein of approx. 118 kDa. The deduced protein sequence exhibits a very high homology to other ubiquitin-activating enzymes identified in a variety of organisms. Northern blot analysis reveals a single transcript of approx. 3.5 kb in all the rabbit tissues examined. The entire coding region of the rabbit E1 cDNA has been expressed as a his-tagged protein. The recombinant protein has been verified by its ability to cross-react with anti-human E1 antibodies. Ubiquitin thiolester assay shows that the recombinant rabbit E1 protein is functional.


Asunto(s)
Ligasas/genética , Ligasas/metabolismo , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Western Blotting , Clonación Molecular , Reacciones Cruzadas , Escherichia coli/genética , Humanos , Ligasas/inmunología , Datos de Secuencia Molecular , Conejos , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/metabolismo , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Distribución Tisular , Enzimas Activadoras de Ubiquitina , Ubiquitina-Proteína Ligasas
6.
Gene ; 256(1-2): 113-21, 2000 Oct 03.
Artículo en Inglés | MEDLINE | ID: mdl-11054541

RESUMEN

We describe the cloning and expression of cDNAs encoding a novel human protein of 208 amino acid residues with a predicted molecular mass of 22.6kDa and its mouse homologue. We name this protein as AWP1 (associated with PRK1). AWP1 is a ubiquitously expressed protein, and the Awp1 gene is switched on during early human and mouse development. When expressed in COS-1 cells, the Myc-tagged AWP1 has an apparent molecular mass higher than that deduced from its amino acid sequence. AWP1 possesses a conserved zf-A20 zinc finger domain at its N-terminal and a zf-AN1 zinc finger domain at its C-terminal. Co-immunoprecipitation experiments revealed that mouse AWP1 specifically interacts with a rat serine/threonine protein kinase PRK1 in vivo. Hence, AWP1 may play a regulatory role in mammalian signal transduction pathways.


Asunto(s)
Proteínas Adaptadoras Transductoras de Señales , Proteínas Portadoras/genética , Proteínas de Plantas , Proteínas/genética , Proteínas Tirosina Quinasas Receptoras/metabolismo , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Northern Blotting , Células COS , Proteínas Portadoras/metabolismo , Mapeo Cromosómico , Cromosomas Humanos Par 15/genética , Clonación Molecular , ADN Complementario/química , ADN Complementario/genética , Escherichia coli/genética , Femenino , Expresión Génica , Glutatión Transferasa/genética , Glutatión Transferasa/metabolismo , Humanos , Ratones , Datos de Secuencia Molecular , Unión Proteica , Proteínas Serina-Treonina Quinasas , Proteínas/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Proteínas Tirosina Quinasas Receptoras/genética , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Alineación de Secuencia , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Distribución Tisular , Dedos de Zinc
7.
FEBS Lett ; 488(3): 201-5, 2001 Jan 19.
Artículo en Inglés | MEDLINE | ID: mdl-11163772

RESUMEN

By the use of the yeast two-hybrid screen we have identified two proteins that interacted with UCH37: S14, which is a subunit of PA700 and a novel protein, UIP1 (UCH37 interacting protein 1). The interaction of UCH37 with S14 or UIP1 was confirmed by in vitro binding assay and in vivo co-immunoprecipitation analysis. The C-terminal extension of UCH37 is essential for interaction with S14 or UIP1 as shown by the yeast two-hybrid assay and the in vitro binding assay. Furthermore, UIP1 blocked the interaction between UCH37 and S14 in vitro.


Asunto(s)
Proteínas Portadoras/metabolismo , Complejo de la Endopetidasa Proteasomal , Proteínas/metabolismo , Tioléster Hidrolasas/metabolismo , Secuencia de Aminoácidos , Sitios de Unión , Unión Competitiva , Western Blotting , Carboxipeptidasas , Proteínas Portadoras/química , Proteínas Portadoras/genética , Perfilación de la Expresión Génica , Humanos , Datos de Secuencia Molecular , Pruebas de Precipitina , Unión Proteica , Subunidades de Proteína , Proteínas/química , Proteínas/genética , ARN Mensajero/análisis , ARN Mensajero/genética , Alineación de Secuencia , Tioléster Hidrolasas/química , Tioléster Hidrolasas/genética , Técnicas del Sistema de Dos Híbridos , Ubiquitina Tiolesterasa
8.
Biochem Pharmacol ; 41(5): 669-75, 1991 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-1998524

RESUMEN

Thirty-three different flavonoids were screened for their ability to influence ATP-dependent Ca2+ uptake by rat liver plasma membrane vesicles. Nine of the flavonoids, at a concentration of 100 microM inhibited Ca2+ uptake by more than 20%. The remaining 24 flavonoids exhibited little or no effect. The relative order of potency of the more biologically active flavonoids was myricetin greater than butein greater than phloretin = luteolin greater than eriodictyol = silybin. Myricitrin and phloridzin, the glycosides of myricetin and phloretin, respectively, had no effect. The degree of inhibition caused by myricetin was concentration dependent and was also affected by the preincubation time. After 10 min of preincubation, 52 microM myricetin lowered the initial rate of 45Ca uptake by 50%. The inhibition by myricetin was non-competitive with respect to Mg-ATP and of a mixed type with respect to Ca2+. At a concentration of 100 microM, myricetin had no effect on several plasma membrane enzymes such as 5'-nucleotidase, alkaline phosphatase and a Ca2(+)-activated ATPase but inhibited K(+)-dependent p-nitrophenyl phosphatase by 83%. The ATP-dependent Ca2+ transport systems located on the plasma membrane or endoplasmic reticulum derived from other tissues were also inhibited by myricetin. Analysis of the structure-activity relationship revealed that lipid solubility and polyhydroxylation particularly at positions 5,7,3' and 4' of the flavonoid ring structure enhanced the ability of the flavonoid to inhibit Ca2+ uptake. The results suggest that inhibition of Ca2+ transport activity probably involves the interaction of the phenolic groups of the flavonoid with the Ca2+ transporting protein.


Asunto(s)
Calcio/metabolismo , Membrana Celular/efectos de los fármacos , Flavonoides/farmacología , Hígado/efectos de los fármacos , Adenosina Trifosfato/farmacología , Animales , Transporte Biológico/efectos de los fármacos , Membrana Celular/enzimología , Relación Dosis-Respuesta a Droga , Hígado/enzimología , Luteolina , Quercetina/farmacología , Ratas , Relación Estructura-Actividad
9.
Singapore Med J ; 40(6): 410-5, 1999 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-10489510

RESUMEN

AIM OF STUDY: This study examines the level of knowledge among youths in Singapore regarding HIV transmission and their attitudes towards working with a HIV-infected person at the workplace. METHOD: Respondents consist of 413 youths from three educational institutions in Singapore. The survey was administered to classes which were randomly selected by the liaison persons of these three educational institutions. RESULTS: Findings of this study suggest that youths in Singapore are generally clear that HIV can be transmitted through sexual contact, blood transfusion and from a woman to her unborn child. However, our data also suggest that a sizeable number of respondents still possess a number of misconceptions about how HIV can be transmitted. While available scientific data suggest that HIV cannot be transmitted through casual contact at the workplace, results of this study suggest that some elements of uncertainty and fear still prevail. This is an interesting finding as it suggests that while AIDS education and campaigns may increase knowledge and awareness about HIV transmission, they do not really reduce personal concern about the possibility of infection and the potential stigma associated with working with HIV-infected persons. CONCLUSION: The implications of our findings on AIDS education are discussed.


Asunto(s)
Infecciones por VIH/psicología , Conocimientos, Actitudes y Práctica en Salud , Prejuicio , Adulto , Miedo , Femenino , Infecciones por VIH/transmisión , Humanos , Masculino , Educación del Paciente como Asunto , Singapur , Lugar de Trabajo
10.
J Soc Psychol ; 140(6): 740-50, 2000 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-11195725

RESUMEN

The authors examined the perceived job image of police officers in Singapore and its differential effects on their work-related attitudes (e.g., job satisfaction, organizational commitment, and intention to quit). The authors obtained data from questionnaire surveys and focus-group interviews. Perceived job image consisted of 4 dimensions: (a) prestige, (b) integrity, (c) competence, and (d) nonroutine job nature. Results of hierarchical regression analyses suggested that the first 2 dimensions of the perceived job image construct were salient in affecting the police officers' work-related attitudes.


Asunto(s)
Actitud/etnología , Perfil Laboral , Policia , Autoimagen , Percepción Social , Adulto , Análisis Factorial , Femenino , Grupos Focales , Humanos , Satisfacción en el Trabajo , Masculino , Lealtad del Personal , Análisis de Regresión , Singapur , Encuestas y Cuestionarios
13.
Biochem Int ; 7(4): 511-8, 1983 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-6207827

RESUMEN

Calmodulin present in rat parotid homogenates activated cyclic AMP phosphodiesterase activity by 8 to 10 fold. The activation was Ca2+-dependent and reversed by trifluoperazine. Half-maximal inhibition required 12 microM trifluoperazine. Incubation of parotid slices with up to 40 microM trifluoperazine had no effect on the basal rate of amylase and K+ release or on cellular ATP content. Isoproterenol stimulated glucose utilization and substance P stimulated amylase secretion were also unaffected by 40 microM trifluoperazine. 20 or 40 microM Trifluoperazine however inhibited amylase secretion induced by isoproterenol, dibutyryl cyclic AMP, carbamoylcholine or phenylephrine. The possible involvement of calmodulin in regulating enzyme secretion following stimulation of the parotid gland with the various types of agonists is discussed.


Asunto(s)
3',5'-AMP Cíclico Fosfodiesterasas/metabolismo , Calmodulina/fisiología , Glándula Parótida/fisiología , Trifluoperazina/farmacología , Amilasas/metabolismo , Animales , Calcio/farmacología , Bovinos , Activación Enzimática , Glucosa/metabolismo , Cinética , Masculino , Miocardio/enzimología , Glándula Parótida/efectos de los fármacos , Glándula Parótida/metabolismo , Potasio/metabolismo , Ratas , Ratas Endogámicas
14.
Biochem J ; 208(3): 789-94, 1982 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-6925974

RESUMEN

Rat parotid gland homogenates were fractionated into mitochondrial, heavy microsomal and light microsomal fractions by differential centrifugation. ATP-dependent 45Ca2+ uptake by the subcellular fractions paralleled the distribution of NADPH-cytochrome c reductase, an enzyme associated with the endoplasmic reticulum. The highest rate of Ca2+ uptake was found in the heavy microsomal fraction. Ca2+ uptake by this fraction was dependent on the presence of ATP and was sustained at a linear rate by 5 mM-oxalate. Inhibitors of mitochondrial Ca2+ transport had no effect on the rate of Ca2+ uptake. Na+ and K+ stimulated Ca2+ uptake. At optimal concentrations. Na+ stimulated Ca2+ uptake by 120% and K+ stimulated Ca2+ uptake by 260%. Decreasing the pH from 7.4 to 6.8 had little effect on Ca2+ uptake. The Km for Ca2+ uptake was 3.7 microM free Ca2+ and 0.19 mM-ATP. Vanadate inhibited Ca2+ uptake; 60 microM-vanadate inhibited the rate of Ca2+ accumulation by 50%. It is concluded that the ATP-dependent Ca2+ transport system is located on the endoplasmic reticulum and may play a role in maintaining intracellular levels of free Ca2+ within a narrow range of concentration.


Asunto(s)
Calcio/metabolismo , Glándula Parótida/metabolismo , Adenosina Trifosfato/metabolismo , Animales , Transporte Biológico Activo/efectos de los fármacos , Técnicas In Vitro , Cinética , Masculino , Microsomas/efectos de los fármacos , Microsomas/metabolismo , Glándula Parótida/efectos de los fármacos , Potasio/farmacología , Ratas , Ratas Endogámicas , Sodio/farmacología , Fracciones Subcelulares/metabolismo , Vanadatos , Vanadio/farmacología
15.
Biochem Int ; 14(5): 921-32, 1987 May.
Artículo en Inglés | MEDLINE | ID: mdl-3454646

RESUMEN

A membrane fraction enriched in plasma membrane marker enzymes K+-dependent p-nitrophenyl phosphatase, 5'-nucleotidase and alkaline phosphatase was prepared from rat parotid glands using Percoll self-forming gradient. This fraction contained an ATP-dependent CA2+ transport system which was distinct from those located on the endoplasmic reticulum and mitochondria of parotid glands. The Km for ATP was 0.57 +/- 0.07 mM (n = 3). Nucleotides other than ATP such as ADP, AMP, GTP, CTP, UTP or ITP were unable to support significant Ca2+ uptake. ATP-dependent Ca2+ uptake displayed sigmoidal kinetics with respect to free Ca2+ concentration with a Hill coefficient of 2.02. The K0.5 for Ca2+ was 44 +/- 3.1 nM (n = 3) and the average Vmax was 13.5 +/- 1.1 nmol/min per mg of protein. The pH optimum was 7.2. Trifluorperazine inhibited Ca2+ transport with half maximal inhibition observed at 30.8 microM. Complete inhibition was observed at 70 microM trifluorperazine. Exogenous calmodulin however had no effect on the rate of transport. Na+ and K+ ions activated Ca2+ transport at 20 to 30 mM ion concentrations. Higher concentrations of Na+ or K+ were inhibitory.


Asunto(s)
Adenosina Trifosfato/farmacología , Calcio/farmacocinética , Glándula Parótida/metabolismo , Animales , Transporte Biológico/efectos de los fármacos , Membrana Celular/metabolismo , Cinética , Masculino , Glándula Parótida/enzimología , Potasio/farmacología , Ratas , Ratas Endogámicas , Sodio/farmacología , Trifluoperazina/farmacología
16.
Biochem Int ; 14(2): 327-36, 1987 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-3034281

RESUMEN

Approximately 94% of rat parotid cyclic AMP phosphodiesterase activity measured at a substrate concentration of 0.1 microM cyclic AMP was found in the 100,000 X g supernatant while the remaining enzyme activity was in the particulate fraction. Incubation of parotid slices with 10 microM isoproterenol resulted in approximately 40% activation of the cyclic AMP phosphodiesterase activity of the 100,000 X g supernatant. The enzyme activity in the particulate fraction was unaffected. The activation resulted from an increase in the value of the Vmax while the apparent Km (0.51 microM) was unaffected. The concentration of isoproterenol required to give half-maximal activation was 0.34 microM. The activation was rapid, became significant after 2 min and reached maximum after 30 min incubation of the parotid slices with isoproterenol. The activation of the enzyme activity by isoproterenol could be blocked by propanolol but was unaffected by cycloheximide. Dibutyryl-cyclic AMP was also effective while phenylephrine and carbamylcholine were ineffective in increasing the activity of the enzyme.


Asunto(s)
3',5'-AMP Cíclico Fosfodiesterasas/metabolismo , Isoproterenol/farmacología , Glándula Parótida/enzimología , 3',5'-AMP Cíclico Fosfodiesterasas/antagonistas & inhibidores , Animales , Bucladesina/farmacología , Carbacol/farmacología , AMP Cíclico/metabolismo , Cicloheximida/farmacología , Activación Enzimática/efectos de los fármacos , Cinética , Masculino , Fenilefrina/farmacología , Propranolol/farmacología , Ratas , Ratas Endogámicas
17.
Biochem Med Metab Biol ; 45(2): 209-15, 1991 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-1831992

RESUMEN

Myricetin, a flavonoid, potently inhibits human erythrocyte plasma membrane Ca(2+)-pumping ATPase activity: half-maximal inhibition of the basal and calmodulin-stimulated activity is obtained with 6 microM myricetin. Inhibition of the Ca(2+)-ATPase by myricetin is observed at all concentrations of free Ca2+ from 10(-8)M to 10(-5)M. The extent of inhibition of the Ca(2+)-ATPase is dependent on the time of preincubation of the plasma membranes with myricetin. Inhibition of the Ca(2+)-ATPase by myricetin is not reversed by excess calmodulin. It is concluded that calmodulin does not mediate myricetin's inhibition of human erythrocyte plasma membrane Ca(2+)-pumping ATPase.


Asunto(s)
ATPasas Transportadoras de Calcio/sangre , Calmodulina/sangre , Membrana Eritrocítica/enzimología , Flavonoides/farmacología , Anticuerpos , Calcio/sangre , ATPasas Transportadoras de Calcio/antagonistas & inhibidores , Calmodulina/inmunología , Calmodulina/farmacología , Ácido Egtácico/farmacología , Humanos , Cinética
18.
Proc Natl Acad Sci U S A ; 83(20): 7765-9, 1986 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-2945205

RESUMEN

Human beta-interferon stimulates a 4-fold increase in the concentration of diacyglycerol and a 2-fold increase in the concentration of inositol monophosphate in Daudi (human B-lymphoblastoid) cells within 30 sec of exposure of the cells to interferon. The increase in diacylglycerol and in inositol monophosphate is transient and the concentrations of these compounds decrease to basal levels within 10 min. Preincubation of human beta-interferon with anti-interferon antibodies inhibits this effect as well as the binding of interferon to Daudi cells. Diacylglycerol concentrations were unaffected in mouse A9 cells (fibroblasts) incubated with human beta-interferon and in Daudi cells incubated with human gamma-interferon. Mouse A9 cells are insensitive to human interferon and Daudi cells are insensitive to human gamma-interferon. The magnitude of the increase in diacylglycerol concentration stimulated by interferon can be correlated to the interferon-induced inhibition of Daudi cell division in a dose-responsive manner. Phorbol 12-myristate 13-acetate also inhibits Daudi cell division in a dose-responsive manner. It is likely that the sharp and transient increase in diacylglycerol concentration represents one of the early biochemical changes in Daudi cells exposed to interferon.


Asunto(s)
Linfocitos B/análisis , Diglicéridos/análisis , Glicéridos/análisis , Interferón Tipo I/farmacología , Linfocitos B/efectos de los fármacos , Calcio/análisis , División Celular/efectos de los fármacos , Línea Celular , Relación Dosis-Respuesta a Droga , Humanos , Fosfatos de Inositol/análisis , Interferón Tipo I/inmunología , Receptores Inmunológicos/metabolismo , Receptores de Interferón , Acetato de Tetradecanoilforbol/farmacología
19.
Biochem Biophys Res Commun ; 272(1): 270-5, 2000 May 27.
Artículo en Inglés | MEDLINE | ID: mdl-10872838

RESUMEN

We have identified a 26S proteasome-associated ubiquitin carboxyl-terminal hydrolase (UCH) in Schizosaccharomyces pombe. The gene (designated uch2+) encodes a protein containing a UCH catalytic domain at its N-terminus and a short extension at its C-terminus. uch2+ is nonessential as the uch2 null mutant strain showed no significant difference from the wild-type strain. The GFP-tagged Uch2p is localized predominantly to the nuclear periphery, which is similar to the 26S proteasome localization. Deletion of the C-terminal extension of Uch2p resulted in a drastic change of its subcellular localization: it showed a generally diffused distribution instead of a perinuclear pattern. Glycerol gradient centrifugation analysis and coimmunoprecipitation studies of fission yeast extracts using anti-Mts4p antiserum suggest that Uch2p is associated with the 26S proteasome and the association of Uch2p with the 26S proteasome is mediated by its C-terminal extension.


Asunto(s)
Péptido Hidrolasas/metabolismo , Complejo de la Endopetidasa Proteasomal , Schizosaccharomyces/enzimología , Tioléster Hidrolasas/metabolismo , Secuencia de Aminoácidos , Animales , Genes Fúngicos , Ratones , Microscopía Fluorescente , Datos de Secuencia Molecular , Péptido Hidrolasas/aislamiento & purificación , Schizosaccharomyces/genética , Homología de Secuencia de Aminoácido , Especificidad de la Especie , Tioléster Hidrolasas/genética , Tioléster Hidrolasas/aislamiento & purificación , Ubiquitina Tiolesterasa
20.
Biochem Med Metab Biol ; 50(3): 358-62, 1993 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-8123299

RESUMEN

A high-affinity Ca(2+)-ATPase was solubilized from rat parotid plasma membranes and purified by concanavalin A and DEAE-cellulose chromatography. The properties of the purified high-affinity Ca(2+)-ATPase are very different from those of the parotid plasma membrane ATP-dependent Ca2+ pump but appear to be similar to those of a rat liver cell adhesion protein which exhibits high-affinity ecto-Ca(2+)-ATPase activity.


Asunto(s)
ATPasas Transportadoras de Calcio/aislamiento & purificación , Glándula Parótida/enzimología , Animales , ATPasas Transportadoras de Calcio/metabolismo , Membrana Celular/enzimología , Ratas , Ratas Wistar
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