RESUMO
Crude membrane fractions of Dictyostelium discoideum show the capacity to synthesize (1--3H)dolicholphosphate from (1--3H)dolichol. Formation of dolicholphosphate increased continuously over the first 15 min. The reaction rate was nearly linear with respect to the dolichol content up to 150 microM. The phosphate donor for the reaction is CTP. The optimum concentration of CTP is about 0,75 mM. The reaction is dependent on divalent metal ions, magnesium being more effective than calcium or manganese. The activity of the polyisoprenol kinase depends on the course of the early development. Maximum enzyme activities are present 4--6 h after the induction of the differentiation.
Assuntos
Dictyostelium/enzimologia , Fosfotransferases (Aceptor do Grupo Álcool) , Fosfotransferases/metabolismo , Diferenciação Celular , Citidina Trifosfato/metabolismo , Dictyostelium/citologia , Fosfatos de Dolicol/biossíntese , Manose/metabolismo , Microssomos/metabolismo , Especificidade por SubstratoRESUMO
Mannosyltransferases in plasma membranes of Dictyostelium discoideum synthesize polyisoprenylphosphomannosides from exogenous polyisoprenylphosphates and GDP-mannose. The specificity of the enzymes depends on the chain length and the saturation of the polyisoprenols. Maximum activity is reached by a alpha-saturated C-55 polyisoprenylphosphate.
