| First Author | Zhao D | Year | 2007 |
| Journal | Biochim Biophys Acta | Volume | 1768 |
| Issue | 7 | Pages | 1815-21 |
| PubMed ID | 17506977 | Mgi Jnum | J:123627 |
| Mgi Id | MGI:3718928 | Doi | 10.1016/j.bbamem.2007.04.010 |
| Citation | Zhao D, et al. (2007) Comparative transport efficiencies of urea analogues through urea transporter UT-B. Biochim Biophys Acta 1768(7):1815-21 |
| abstractText | 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, methylformamide, ammonium carbamate, 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. |
