Biological cells are complex non-equilibrium systems that cannot survive without efficient supplying of the necessary compounds and removing of wasteful or harmful molecules. A remarkable feature of biological transport is very high efficiency and selectivity, and robustness, i.e., its ability to adjust to fluctuations in cellular environment. Cell transport mechanisms fall into two categories: passive and active transport. In passive transport the molecules are moved by utilizing the concentration and/or electric potential gradients, while active transport utilizes a complex network of biochemical transitions of enzymes to extract energy (typically from ATP hydrolysis) in order to move particles against the gradients and external forces. The motion of molecules in cells also involves cytoskeleton proteins that not only provide molecular tracks for transportation, but also actively participate in transport processes. Understanding mechanisms of transport phenomena has important implications for all cellular processes and for development of new methods to treat many diseases.
One of the most important components of biological transport systems are motor proteins. Motor proteins are enzyme molecules that convert the chemical energy into the mechanical motion. There are significant recent experimental advances in the investigation of these proteins that allowed viewing the dynamics at a single-molecule level. These developments stimulated a lot of efforts to model motor proteins. However, the level of theoretical description is still mostly phenomenological. There is a need for more detailed and more microscopic theoretical models. It seems that it is now a right time to have a workshop that would combine mathematicians and experimentalists working in the area of motor proteins.
Another important subject of biological transport is the translocation of large biomolecules via membrane pores. Recent in vitro experiments investigated in detail the motion of DNA and RNA molecules via alpha-hemolysin membrane proteins. These experiments, that measure the blockages in current through these channels, raised the fundamental question on what is important in the transport of these polymers. At the same time theoretical side of these problems are studied to less degree. It is reasonable to suggest that this subject will greatly benefit from the workshop that combines theoretical and experimental researchers.
For a long time it was assumed that large water-filled channels in membranes act as molecular sieves. However, recent experiments suggest that the molecules moving through these membrane pores experience a specific interaction with the walls that lead to efficient and selective transport. What are the mechanisms of these phenomena remains unclear. There is a strong need for the people from mathematics field to get involved into this area to further advance our under standing of the biological transport.
Thus we propose that for this workshop to focus on the following areas: