Reversed transport of amino acids in Ehrlich cells |
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Authors: | RM Johnstone |
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Institution: | The Department of Biochemistry, McGill University, Montreal H3G 1Y6, Quebec Canada |
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Abstract: | Gramicidin induces a marked Na+-dependent efflux of amino acids from Ehrlich cells. In absence of Na+, gramicidin does not alter the efflux. In presence of gramicidin, glycine efflux is inhibited by methionine and less so by leucine. Glycine efflux caused by HgCl2 is neither Na+ dependent nor inhibitable by amino acids. Neither efflux of inositol which is transported by an Na+-dependent route, nor efflux of several other solutes which are transported by Na+-independent routes, is affected by gramicidin. The antibiotic appears to permit a reversal in the direction of the operation of the Na+-dependent amino acid transport system. The increased efflux is partly, but not entirely, due to an increase in the cellular Na+ concentration and a reduction of the electrochemical potential difference for Na+. |
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