What is the nature of the 'fringe' in protein-protein interactions?

In protein-protein interactions, the 'fringe' refers to the regions of proteins that are more flexible and often involved in the interactions with other proteins. These areas are typically hydrophilic and located at the periphery of the protein structure. Their hydrophilic nature allows them to interact with the aqueous environment, facilitating the formation of complexes with other proteins, as they can engage in hydrogen bonding and other interactions with polar or charged residues.

The flexibility of these fringe regions enables proteins to adopt various conformations, promoting better fit and interaction with partner proteins. This dynamic behavior is essential for many biological processes, including signaling pathways and enzyme regulation, where transient and reversible interactions are crucial. Understanding this aspect of protein structure helps clarify how proteins can effectively communicate and collaborate in various cellular functions.