Studies on human porin XIX: Zinc ions reduce the voltage-dependence of human type-1 porin integrated in artificial planar lipid bilayers barium ions do not

We report on the first data concerning the effects of ionic zinc or barium on human type-1 porin. The channel enriched as mature protein from B-lympho cyte crude membranes was integrated into artificial planar lipid bilayers a nd both agonists were applied as their chloride salts at 100 mu M. Relative conductance was measured from -80 to 80 mV. The presence of Zn2+ resulted in a distinct reduction of the voltage dependence of the channel, the effec t appearing to be symmetric. The addition of Ba2+ did not produce any measu rable effect on human porin. According to our knowledge we present the firs t results on the interaction of bivalent metal ions and eukaryotic type-1 p orin. The putative physiological relevance of the data is discussed. (C) 19 99 Academic Press.