Biological media are far from ideal: inside living cells more than 30 % of the volume is occupied by hundreds of thousands of macromolecules. In certain situations, the concentration can be even higher. In the eye lens of artic fish, for example, proteins account for more than 59 % of the volume. It is now recognized that crowding is a crucial factor. As it is widely recognized, crowding is a real control mechanism in biological processes occurring in the cell. Crowding effects, for example, regulate hormones and mediators, while there is increasing evidence that also the elusive bases of allosteric induction in proteins involved in gene regulation can be somehow rationalized in terms of the concentration of neighboring effector molecules. Other activities in the cell are expected to be affected by the level of crowding, such as trafficking and signaling in cells and bacteria and the functioning of the nuclear pore complex. Despite the fast-growing body of data, there are still fundamental gaps in our knowledge that prevent us from fully understanding how the cellular environment acts in fine-tuning and modulating biological phenomena occurring in vivo, such as inter-molecular signaling and gene regulation. This Frontiers Research Topic will showcase a collection of contributions from biologists, chemists, physicists, experimental and theoretical researchers all interested in this fast-growing field. The aim is to report on the current state of the art, placing great emphasis on the need for an interdisciplinary approach to solve current open problems and shape the forthcoming challenges.
Biological media are far from ideal: inside living cells more than 30 % of the volume is occupied by hundreds of thousands of macromolecules. In certain situations, the concentration can be even higher. In the eye lens of artic fish, for example, proteins account for more than 59 % of the volume. It is now recognized that crowding is a crucial factor. As it is widely recognized, crowding is a real control mechanism in biological processes occurring in the cell. Crowding effects, for example, regulate hormones and mediators, while there is increasing evidence that also the elusive bases of allosteric induction in proteins involved in gene regulation can be somehow rationalized in terms of the concentration of neighboring effector molecules. Other activities in the cell are expected to be affected by the level of crowding, such as trafficking and signaling in cells and bacteria and the functioning of the nuclear pore complex. Despite the fast-growing body of data, there are still fundamental gaps in our knowledge that prevent us from fully understanding how the cellular environment acts in fine-tuning and modulating biological phenomena occurring in vivo, such as inter-molecular signaling and gene regulation. This Frontiers Research Topic will showcase a collection of contributions from biologists, chemists, physicists, experimental and theoretical researchers all interested in this fast-growing field. The aim is to report on the current state of the art, placing great emphasis on the need for an interdisciplinary approach to solve current open problems and shape the forthcoming challenges.