Base de dados : LILACS
Pesquisa : D08.811.277.040.330.300.200.800 [Categoria DeCS]
Referências encontradas : 4 [refinar]
Mostrando: 1 .. 4   no formato [Detalhado]

página 1 de 1

  1 / 4 LILACS  
              next record last record
seleciona
para imprimir
Fotocópia
Texto completo SciELO Chile
Texto completo
Id: lil-356878
Autor: Kosoy, Ana; Moller, Carolina; Perdomo, Deisy; Bubis, Jose.
Título: Identification of functionally important acidic residues in transducin by group-specific labeling
Fonte: Biol. Res;36(3/4):389-404, 2003. ilus, graf.
Idioma: en.
Resumo: Transducin (T), a GTP-binding protein involved in phototransduction of rod photoreceptor cells, is a heterotrimer arranged as two units, the alpha-subunit (T alpha) and the beta gamma-complex (T beta gamma). The role of the carboxyl groups in T was evaluated by labeling with N,N'-dicyclohexylcarbodiimide (DCCD) and 1-ethyl 3-(3-dimethylaminopropyl) carbodiimide (EDC). Only a minor effect on the binding of beta, gamma-imido guanosine 5'-triphosphate (GMPpNp) to T was observed in the presence of the hydrophobic carbodiimide, DCCD. Similarly, the GMPpNp binding activity of the reconstituted holoenzyme was not significantly affected when T alpha was combined with DCCD-treated T beta gamma. However, the binding of guanine nucleotides to the reconstituted T was approximately 50 per cent inhibited when DCCD-labeled T alpha was incubated with T beta gamma. In contrast, treatment of T with the hydrophilic carbodiimide, EDC, completely impaired its GMPpNp-binding ability. EDC-modified T was incapable of interacting with illuminated rhodopsin, as determined by sedimentation experiments. However, rhodopsin only partially protected against the inactivation of T. Additionally, analyses of trypsin digestion patterns showed that fluoroaluminate was not capable of activating the EDC-labeled T sample. The function of the reconstituted holoenzyme was also disrupted when EDC-modified T alpha was combined with T beta gamma, and when EDC-treated T beta gamma was incubated with T alpha.
Descritores: Dicicloexilcarbodi-Imida
Rodopsina
Segmento Externo da Célula Bastonete
Transducina
-Transdução de Sinais
Transducina
Limites: Animais
Bovinos
Responsável: BR1.1 - BIREME


  2 / 4 LILACS  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Id: lil-228604
Autor: Bubis, Jose; Millan, Enrique J; Martinez, R.
Título: Identification of guanine nucleotide binding proteins from Trypanosoma cruzi
Fonte: Biol. Res;26(1/2):177-88, 1993. ilus.
Idioma: en.
Resumo: Guanine nucleotide binding proteins (GTP-binding proteins) function as transducers of signals in different cellular processes. We have identified several GTP-binding proteins in Trypanosoma cruzi by Western blot analyses. Six polypeptide bands, p20, p25, p28, p31, p37 and p38, were specifically detected in epimastigote crude extracts, using polyclonal antibodies directed against transducin (T) or the alpha-subunit of transducin (T alpha). Four of these bands, p28, p31, p37 and p38, were found in both the soluble and the particulate epimastigote fractions. On the other hand, two of the polypeptides, p20 and p25, were observed only in the particulate fraction, and were not solubilized using 0.2 percent Triton X-100 and 0.2 percent Nonidet P-40. A rat monoclonal antibody directed against the ras oncogene, immunorecognized a band with molecular mass of 20,000 daltons, in epimastigote homogenates. In view of their identical apparent molecular weight and solubilization properties, p20, recognized by anti-T or anti-T alpha antibodies, and the 20 KDa band, recognized by anti-ras antibodies, seem to correspond to the same polypeptide. [3H] GDP and [3H] GMP-PNP binding experiments revealed the presence of guanine nucleotide binding proteins in total epimastigote crude extracts, as well as, in the soluble, detergent soluble, and particulate fractions. A primary screening of a T. cruzi cDNA library with anti-T alpha antibodies, followed by secondary and tertiary screenings with anti-ras antibodies yielded six positive clones. One of these clones (Tc-ras1) contains a 600 bp insert which we believe encodes for the ras protein from T. cruzi. On a Northern blot, this cDNA hybridizes to a unique mRNA band of 2.0 Kilobases in epimastigotes
Descritores: Proteínas de Ligação ao GTP/análise
Proteínas de Protozoários/análise
Trypanosoma cruzi/química
-Anticorpos Monoclonais
Biblioteca Gênica
Genes ras/imunologia
Proteínas de Ligação ao GTP/imunologia
Proteínas de Ligação ao GTP/fisiologia
Proteínas de Protozoários/imunologia
Transdução de Sinais
Transducina/imunologia
Trypanosoma cruzi/fisiologia
Tubulina (Proteína)/imunologia
Limites: Animais
Bovinos
Embrião de Galinha
Feminino
Humanos
Camundongos
Coelhos
Ratos
Tipo de Publ: Research Support, Non-U.S. Gov't
Responsável: BR1.1 - BIREME


  3 / 4 LILACS  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Id: lil-228574
Autor: Bubis, J.
Título: Improved purification of transducin subunits from bovine retinal rod outer segments
Fonte: Biol. Res;28(4):291-9, 1995.
Idioma: en.
Resumo: Transducin serves as a mediator between the receptor protein, rhodopsin, and the effector protein, cGMP phosphodiesterase, in the visual process. Transducin is a protein composed of three polypeptides: T alpha, T beta, and T gamma, and acts as two functional units, the alpha-subunit and the beta gamma-complex. In the present study, I describe an efficient and fast method of purifying T alpha and T beta gamma using chromatography on a blue agarose column connected in tandem with an omega-amino octylagarose column. The recombination of T alpha and T beta gamma reconstitutes the functional heterotrimeric holoprotein, as demonstrated by the recovery of three native properties of transducin: 1) its capacity to exchange guanine nucleotide, 2) its GTP hydrolytic activity, and 3) the ADP-ribosylation of T alpha catalysed by pertussis toxin
Descritores: Rodopsina/química
Segmento Externo da Célula Bastonete/química
Transducina/isolamento & purificação
-Cromatografia em Agarose/métodos
Eletroforese em Gel de Poliacrilamida
Inibidores da Síntese de Proteínas/farmacologia
Sefarose/análogos & derivados
Sefarose/farmacologia
Triazinas/farmacologia
Limites: Animais
Bovinos
Tipo de Publ: Research Support, Non-U.S. Gov't
Responsável: BR1.1 - BIREME


  4 / 4 LILACS  
              first record previous record
seleciona
para imprimir
Fotocópia
Id: lil-225980
Autor: Bubis, José.
Título: Effect of detergents and lipids on transducin photoactivation by rhodopsin
Fonte: Biol. Res;31(1):59-71, 1998. tab, graf.
Idioma: en.
Projeto: Universidad Simón Bolívar. Decanato de Investigación y Desarrollo.
Resumo: Rhodopsin samples, isolated using four different extraction procedures, were used to investigate the photodependent activation of the GTPase activity of transducin. A complete inhibition of transducin light-dependent GTP hydrolytic activity was observed when rhodopsin purified in the presence of 1 per cent digitonin, following rod outer segment (ROS) solubilization with 1 per cent 3-[(3-cholamidopropyl) dimethylammonio]-1-propane-sulfonate (CHAPS), WAS used for its activation [0 pmol of inorganic phosphate (Pi) released/min/pmol of rhodopsin]. Rhodopsin, isolated in the presence of 1 per cent digitonin following ROS solubilization with 1 per cent digitonin, was capable of stimulating slightly transducin GTPase activity, with an initial rate of 1 pmol of GTP hydrolyzed/min/pmol of rhodopsin. However, rhodopsin purified in the presence of 0.2 per cent n-dodecyl-beta-D-maltoside (DM), following ROS solubilization with either 1 per cent CHAPS or 1 per cent DM, stimulated the enzymatic activity of transducin in a light-dependent manner, with an initial rate of 5 pmol of Pi released/min/pmol of rhodopsin. Addition of 0.075 per cent egg phosphatidylcholine (PC) to the four different solubilized rhodopsin samples significantly enhanced light-stimulated GTP hydrolysis by transducin, with initial rates increasing from 0 to 1, 1 to 2, and 5 to 30 pmol of Pi released/min/pmol of rhodopsin, respectively. Furthermore, DM-solubilized rhodopsin induced the hydrolysis of the maximun amount of GTP by transducin at 0.0075 per cent PC, while digitonin-solubilized rhodopsin only stimulated the GTPase activity of transducin to a similar value, when the amount of the photoreceptor protein was increased 4-fold and 0.15 per cent PC was added to the assay mixture. These results suggest that the effective photoactivation of transducin by rhodopsin requires phospholipids, which seem to be differentially eliminated with the detergent extraction procedure utilized during ROS membranes solubilization and photopigment isolation.
Descritores: Detergentes
Lipídeos
Estimulação Luminosa
Rodopsina
Transducina
-GTP Fosfo-Hidrolases/metabolismo
Retina
Rodopsina/isolamento & purificação
Transducina/isolamento & purificação
Transducina/metabolismo
Limites: Animais
Bovinos
Responsável: BR1.1 - BIREME



página 1 de 1
   


Refinar a pesquisa
  Base de dados : Formulário avançado   

    Pesquisar no campo  
1  
2
3
 
           



Search engine: iAH v2.6 powered by WWWISIS

BIREME/OPAS/OMS - Centro Latino-Americano e do Caribe de Informação em Ciências da Saúde