Functional asymmetry of the amine transporter from chromaffin granules.

摘要: The studies presented in this communication describe the existence of a pH-dependent kinetic barrier amine translocation membrane vesicles isolated from chromaffin granules bovine adrenal medulla. This prevents efflux amines previously accumulated vesicles. In these preparations, once is accumulated, there no further need for ATP. would suggest low permeability membrane, both to ions and amine. addition, we show that under conditions which thermodynamically favour kinetically blocked. block due rapid protonation transporter interior vesicle. Net can be induced by agents bring upon an alkalinization internal pH such as ammonium salts or nigericin. On other hand, rate exchange with extravesicular substrate almost identical at various values tested. physiological implications mechanism are discussed.