Assuntos
Anticorpos Monoclonais/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Sistemas de Liberação de Medicamentos/métodos , Receptores ErbB/genética , Testes Genéticos/métodos , Proteínas Proto-Oncogênicas/genética , Proteínas ras/genética , Análise Mutacional de DNA , Predisposição Genética para Doença/genética , Humanos , Mutação/genética , Seleção de Pacientes , Proteínas Proto-Oncogênicas p21(ras)RESUMO
Data concerning membrane binding of glutathione reductase (GSSG-R) have been reexamined with respect to the following experimental conditions: 1. Haemolysis and membrane preparation; 2. influence of nonionic detergents (Triton X-100, Lubrol PX). Haemolysis and membrane preparations performed at physiological ionic strength, and reduced glutathione concentration do not give any evidence for binding of GSSG-R to the erythrocyte membrane. Under hypotonic conditions of ghost preparation about 2% of the total cellular GSSG-R activity are membrane bound, indicating weak enzyme association at low ionic strength only.
Assuntos
Membrana Eritrocítica/enzimologia , Eritrócitos/enzimologia , Glutationa Redutase/sangue , Adulto , Detergentes/farmacologia , Hemólise , Humanos , Técnicas In Vitro , Proteínas de Membrana/metabolismo , Concentração OsmolarRESUMO
The time course of 32P incorporation into ATP and monoesterified membrane phosphatases was studied within 1 h of incubation of intact human erythrocytes. Analysis of membrane proteins and phospholipids showed dynamically exchanged phosphates mainly in the phospholipid fraction. The extent of ATP turnover by spectrin band 2 polypeptide phosphorylation was very small. The 32P-ATP and the membrane 32P-phosphate label could be chased via the metabolism by the addition of extracellular Pi. From the relative changes in the specific radioactivity of ATP and of the membrane phosphate in intact erythrocytes we assume that about 60% of the erythrocyte ATP production are linked to the ATP consumption by the rapid polyphosphoinositide turnover. It is conceivable that there is a connection between the protein factors modifying the affinity of (Ca2+, Mg2+)-ATPase and the metabolism of the polyphosphoinositides in the erythrocyte membrane.
Assuntos
Trifosfato de Adenosina/sangue , Membrana Eritrocítica/metabolismo , Eritrócitos/metabolismo , Humanos , Cinética , Lipídeos de Membrana/sangue , Proteínas de Membrana/sangue , Fosfatos/metabolismo , Fosfolipídeos/sangue , Fosforilação , Espectrina/metabolismoRESUMO
Highly purified GAPD preparations from human erythrocytes and skeletal muscle have been used as immunogenes in rabbits. The antibodies produced readily precipitated their antigens and also inhibited their enzymatic activities. An immunochemical evaluation of the precipitability of both enzymes exhibited no immunochemical differences between them. Furthermore, the antibodies were tested against several tissue homogenates from man and revealed an identical precipitability. The identical cross-reactivity indicating a lack of antigenic differences support the absence of GAPD-isoenyzmes in man. The amount of GAPD in several organ extracts was estimated by the technique of single radial immunodiffusion. Furthermore it was demonstrated that the GAPD is bound to the membrane only under hypotonic conditions of hemolysis, while under approximated intracellular conditions of hemolysis the GAPD is not membrane bound.
Assuntos
Formação de Anticorpos , Antígenos , Gliceraldeído-3-Fosfato Desidrogenases/imunologia , Animais , Especificidade de Anticorpos , Reações Cruzadas , Eritrócitos/enzimologia , Isoenzimas , Masculino , Músculos/enzimologia , Testes de Precipitina , CoelhosRESUMO
Adenylate cyclase activity stimulated by fluoride was studied in membranes from different red cell populations produced by bleeding anemia in rabbits. The cells were fractionated by density gradient centrifugation in dextrane. The highest adenylate cyclase activity was found in the reticulocyte fractions with low density and the highest RNA-content. No activity was found in the mature erythrocytes. It is apparent that the adenylate cyclase in the red blood cells can serve as a useful indicator of the maturation process.
