Anion-Sensitive Mg2+ ATP-Dependent Proton Pumping in Microsomal Membranes from Phycomyces blakesleeanus Bgff
AUTOR(ES)
Rausch, Thomas
RESUMO
A light microsomal membrane fraction (collected on 28% weight/volume sucrose) from young mycelia of Phycomyces blakesleeanus Bgff. stationary cultures exhibited Mg2+ ATP-dependent proton pumping as monitored with the dye neutral red or by accumulation of [14C]methylamine. The substrate kinetics for ATP (Km(ATP) 1.1 millimolar in the presence of 2 millimolar Mg2+), the competitive inhibition by ADP (Ki(ADP) 0.8 millimolar), the anion sensitivity (stimulation by Cl−, inhibition by NO3− and SO42−), the reversal of acidification by Ca2+, the inhibition by diethylstilbestrol and dicyclohexylcarbodiimide, as well as the absence of any inhibition by azide, molybdate, and vanadate strongly suggest a tonoplast-type ATPase driven proton pumping. The same membrane fraction showed no pyrophosphate driven H+-translocation. Electron microscopic examination of the fungal mycelium demonstrated the presence of vacuoles of different sizes and other nonidentified vesicles but no typical Golgi stacks.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1055734Documentos Relacionados
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