caa a22 4500 445321210 CHVBK 20180317142704.0 cr unu---uuuuu 170323e20111201xx s 000 0 eng 10.1007/s10534-011-9479-5 doi (NATIONALLICENCE)springer-10.1007/s10534-011-9479-5 Effects of heavy metal cations on the mitochondrial ornithine/citrulline transporter reconstituted in liposomes [Elektronische Daten] [Annamaria Tonazzi, Cesare Indiveri] The effect of heavy metal cations on the mitochondrial ornithine/citrulline transporter was tested in proteoliposomes reconstituted with the protein purified from rat liver. The transport activity was measured as [3H]ornithine uptake in proteoliposomes containing internal ornithine (ornithine/ornithine antiport mode) or as [3H]ornithine efflux in the absence of external substrate (ornithine/H+ transport mode). 0.1mM Cu2+, Pb2+, Hg2+, Cd2+ and Zn2+ strongly inhibited (more than 85%) the antiport; whereas Mn2+, Co2+ and Ni2+ inhibited less efficiently (25, 47 and 69%, respectively). The IC50 values of the transporter for the different metal ions ranged from 0.71 to 350μM. Co2+ and Ni2+ also inhibited the [3H]ornithine efflux whereas Cu2+, Pb2+, Hg2+, Cd2+ and Zn2+ stimulated the [3H]ornithine efflux. The stimulation of the [3H]ornithine efflux by Cu2+ and Cd2+ (as well as by Pb2+, Hg2+ and Zn2+) was not prevented by NEM and was reversed by DTE. These features indicated that the inhibition of the antiport was due to the interaction of the Cu2+, Pb2+, Hg2+, Cd2+ and Zn2+ with a population of SH groups, of the transporter, responsible for the inhibition of the physiological function; whereas the stimulation of [3H]ornithine efflux was due to the induction of a pore-like function of the transporter caused by interaction of cations with a different population of SH groups. Differently, the inhibition of the ornithine transporter by Ni2+, Co2+ or Mn2+ was caused by interaction with the substrate binding site, as indicated by the competitive or mixed inhibition. Springer Science+Business Media, LLC., 2011 Transport nationallicence Heavy metals nationallicence Liposomes nationallicence Ornithine nationallicence NEM : N-Ethylmaleimide nationallicence DTE : 1,4-Dithioerythritol nationallicence DTNB : 5,5′-Dithiobis (2-nitrobenzoic acid) nationallicence HHH syndrome : Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome nationallicence Tonazzi Annamaria CNR Institute of Biomembranes and Bioenergetics, via Amendola 165/A, 70126, Bari, Italy aut Indiveri Cesare Department of Cellular Biology, University of Calabria, 87036, Arcavacata di Rende, Italy aut BioMetals Springer Netherlands 24/6(2011-12-01), 1205-1215 0966-0844 24:6<1205 2011 24 10534 https://doi.org/10.1007/s10534-011-9479-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10534-011-9479-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Tonazzi Annamaria CNR Institute of Biomembranes and Bioenergetics, via Amendola 165/A, 70126, Bari, Italy aut NATIONALLICENCE 700 1- Indiveri Cesare Department of Cellular Biology, University of Calabria, 87036, Arcavacata di Rende, Italy aut NATIONALLICENCE 773 0- BioMetals Springer Netherlands 24/6(2011-12-01), 1205-1215 0966-0844 24:6<1205 2011 24 10534 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer