The basic asymmetry of Na+-dependent glycine transport in Ehrlich cells |
| |
Authors: | RM Johnstone |
| |
Institution: | Department of Biochemistry, McGill University, Montreal, Quebec, H3G 1Y6 Canada |
| |
Abstract: | Influx and efflux of glycine have been examined as a function of external and internal Na+ concentrations, respectively, when . With it was found that at comparable external and cellular Na+ levels, the for efflux was larger by an order of magnitude than the value for influx and the for efflux was several times greater than the for influx. For both fluxes the major effect of Na+ was to decrease the value. The observations are consistent with the conclusion that the Na+-dependent transport system is asymmetric per se. Influx and efflux of glycine were increased in a near linear manner by increasing the Na+ concentration from 13 to 100 mM, the half-time for glycine equilibration being a function of the Na+ concentration in absence of an electrochemical potential difference for Na+. In Na+-free media () equilibration of glycine between cells and medium was not achieved after 60 min at 25°C. With , efflux (or uptake) of glycine was not affected by internal (or external) K+ between 20 and 120 mM suggesting that K+ plays no direct role in Na+-dependent transport of glycine in Ehrlich cells. |
| |
Keywords: | Hepes |
本文献已被 ScienceDirect 等数据库收录! |
|