Comparative transport efficiencies of urea analogues through urea transporter UT-B
Comparative transport efficiencies of urea analogues through urea transporter UT-B
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DOI：
10.1016/j.bbamem.2007.04.010
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发表时间：
2007-07-01
影响因子：
3.4
通讯作者：
Yang, Baoxue
中科院分区：
文献类型：
--
作者：
Zhao, Dan;Sonawane, N. D.;Yang, Baoxue
Expression of urea transporter UT-B confers high urea permeability to mammalian erythrocytes. Erythrocyte membranes also permeate various urea analogues, suggesting common transport pathways for urea and structurally similar solutes. In this study, we examined UT-B-facilitated passage of urea analogues and other neutral small solutes by comparing transport properties of wildtype to UT-B-deficient mouse erythrocytes. Stopped-flow light-scattering measurements indicated high UT-B permeability to urea and chemical analogues formamide, acetamide, methylurea, methylformarnide, ammonium carbarnate, and acrylamide, each with P-s > 5.0 x 10(-6) cm/s at 10 degrees C. UT-B genetic knockout and phloretin treatment of wildtype erythrocytes similarly reduced urea analogue permeabilities. Strong temperature dependencies of formamide, acetamide, acrylamide and butyramide transport across UT-B-null membranes (E-a > 10 kcal/mol) suggested efficient diffusion of these amides across lipid bilayers. Urea analogues dimethylurea, acryalmide, methylurea, thiourea and methylformamide inhibited UT-B-mediated urea transport by > 60% in the absence of transmembrane analogue gradients, supporting a pore-blocking mechanism of UT-B inhibition. Differential transport efficiencies of urea and its analogues through UT-B provide insight into chemical interactions between neutral solutes and the UT-B pore. (c) 2007 Elsevier B.V. All rights reserved.
