AN ION-PUMP MECHANISM-BASED ON CHANNEL PROCESSES IN THE NA,K-ATPASE

An ion pump mechanism can be based on channel processes in the Na,K-ATPase, where conformational changes result from charge shifts within the protein during enzyme activity. A shift of charge, from a high charge density region to a low density region, causes a channel to open and also affects the ionic gradients (freeing bound counter-ions in the high charge region, and binding counter-ions in the low charge region). The simultaneous changes can result in a transient reversed local concentration gradient driving ions through the opened channel. If the enzyme surfaces bind ions preferentially, a local gradient of particular ions can be created.