An experimental test for cyclic versus linear transport models. The mechanisms of glucose and choline transport in erythrocytes.

摘要: Numerous mechanisms have been suggested to explain transport across biological membranes, all of which fall into one or the other two distinct categories. In some, substrate sites in free carrier are simultaneously exposed on membrane surfaces, while others a site is alternately opposite sides. Either group could account for active and facilitated transport, as well accelerated exchange, countertransport, hyperbolic saturation curves. A simple kinetic test described here distinguishes between these classes. The depends measurements rates presence reversible competitive inhibitors inside outside cell. Experiments reported glucose system erythrocytes involving phloretin cytochalasin B, choline same cells, with nontransported analogs dimethyl-n-pentyl(2-hydroxyethyl)ammonium ion 2-di-butylaminoethanol. results agreement single site-exposure models, include classical carrier, incompatible dual models. latter therefore rejected explanations transport.