Gating and permeation models of plant channels.

Models of different level are applied to plant membrane transport. For the evaluation of I/V curves, models based on enzyme kinetics, limitation by diffusion and the ion well are described. Physical models of ion-ion interaction deal with the Woodhull model, the multi-site single-file ion pore, the ion-ion ion-water interaction model and the effect of screening. The discussion of channel gating starts with pre-patch evidence of gating and the biological importance of gating. State models play a dominant role in the analysis of patch clamp records. Gating may strongly interfere with permeation models. With respect to this, the limits of temporal resolution are of great importance. The effects of Na(+) and Tl(+) are examples of the influence of fast gating on modelling and the problems of its detection. The highest level of modelling is achieved when the knowledge about the structure of channels is employed for the modelling of gating. Major topics in this field are blockade by ions and phosphorylation.