Molecular Mechanisms of Active Transport in Antiporters: Kinetic Constraints and Efficiency

A vital role in supporting successful functioning of biological cells is played by membrane channels called antiporters. These channel proteins utilize the concentration gradient of one type of species to move another type of species in the opposite direction and against their concentration gradient. It is believed that antiporters operate via alternating conformational transitions that expose these proteins to different sides of the membrane, and that only thermodynamics controls the activation of these channels. Here we explicitly investigate a chemical-kinetic model of antiporters to argue that there are additional kinetic constraints that need to be satisfied for these channels to be operational. This implies that kinetics and not thermodynamics governs the functioning of antiporters. In addition, the efficiency of antiporters is analyzed and the most optimal operating conditions are discussed. Our theoretical analysis clarifies some important aspects of the molecular mechanisms of biological membrane transport.

Automated summary

Antiporters are membrane channel proteins that play a vital role in biological cell functioning by moving species against their concentration gradients. Research indicates that additional kinetic constraints, rather than just thermodynamics, govern the functioning of antiporters, and optimal operating conditions have been discussed for their efficiency. This theoretical analysis sheds light on important aspects of biological membrane transport mechanisms.