Amino-acid transport into cultured tobacco cells |
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Authors: | S. L. Berry H. M. Harrington R. L. Bernstein R. R. Henke |
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Affiliation: | (1) U.S. Department of Energy Comparative Animal Research Laboratory, University of Tennessee, 37830 Oak Ridge, TN, USA;(2) Present address: Department of Genetics, University of Georgia, 30602 Athens, GA, USA;(3) Present address: Department of Biological Sciences, Bowling Green State University, 43403 Bowling Green, OH, USA;(4) Present address: Department of Biological Sciences, San Francisco State University, 94132 San Francisco, CA, USA;(5) Present address: Department of Botany, University of Tennessee, 37916 Knoxville, TN, USA |
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Abstract: | Arginine transport in suspension-cultured cells of Nicotiana tabacum L. cv. Wisconsin-38 was investigated. Cells that were preincubated in the presence of Ca2+ for 6 h prior to transport exhibited stimulated transport rates. After the preincubation treatment, initial rates of uptake were constant for at least 45 min. Arginine accumulated in the cells against a concentration gradient; this accumulation was not the result of exchange diffusion. Arginine uptake over a concentration range of 2.5 M to 1 mM was characterized by simple Michaelis-Menten kinetics with a Km of 0.1 mM and a Vmax of 9,000 nmol g-1 fresh weight h-1. Transport was inhibited by several compounds including carbonylcyanide-m-chlorophenylhydrazone, 2,4-dinitrophenol, N,N-dicyclohexylcarbodiimide, and N-ethylmaleimide. Inhibition by these compounds was not the result of increased efflux resulting from membrane damage. A variety of amino acids and analogs, with the exception of D-arginine, inhibited transport, indicating that arginine transport was mediated by a general L-aminoacid permease. Competition experiments indicated that arginine and lysine exhibited cross-competition for transport, with Ki values similar to respective Km values. Arginine transport and low-affinity lysine transport are probably mediated by the same system in these cells.Abbreviations BTP Bis Tris Propane - CCCP Carbonylcyanide-m-chlorophenylhydrazone - DCCD N,N-dicyclohexylcarbodiimide - DNP 2,4-dinitrophenol - DTT Dithiothreitol - NEM N-ethylmaleimide - MES 2(N-morpholino)ethanesulfonic acid - TCA trichloroacetic acidThis paper is the third in a series on amino-acid transport into cultured tobacco cells. For parts I and II, see Harrington and Henke (1981) and Harrington et al. (1981) |
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Keywords: | Amino-acid transport Arginine Cell culture (tobacco) Nicotiana Transport (arginine) |
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