Researchers at the Universities of Göttingen and Warwick investigated the structure and mechanics of the main component of the cytoskeleton of the cell: a protein known as actin. Actin is found in all living cells where it has a range of important functions -- from muscle contraction to cell signalling and cell shape. This protein comes in two different varieties termed "isoforms," which are known as gamma actin and beta actin. The difference between the two proteins is miniscule, only a few amino acids at just one part of the molecule vary. Yet this small change has a big impact on the cell. In nature, normally only mixtures of the two isoforms are found.

 

In their study, the researchers separated out the two isoforms and analyzed them individually. The researchers studied the behaviour of networks of filaments, particularly focusing on the unique properties of the individual isoforms. They employed specialized techniques allowing them to assess the mechanics and dynamics of research models of cytoskeletal networks, drawing on expertise in biophysics at Göttingen and bioengineering at Warwick. The results indicate that gamma actin prefers to form rigid networks near the cell's apex, while beta actin preferentially forms parallel bundles with a distinct organizational pattern. This difference is likely to be due to the stronger interaction of gamma actin with specific types of positively charged ions, rendering its networks stiffer than those formed by beta actin. The findings are compelling because they open up new avenues for understanding the intricate dynamics of protein networks within cells.