Protein-Protein Interface

A **protein-protein interface** is the *specific surface region* where two or more proteins come into direct contact to form a protein-protein interaction (PPI). These interfaces consist of distinct arrangements of amino acid residues and can involve a variety of biochemical forces, including hydrophobic contacts, hydrogen bonds, ionic interactions, and van der Waals forces[7][5]. The structural and chemical features of the interface determine the affinity and specificity of the interaction[7]. Protein-protein interfaces are fundamental to the assembly and regulation of protein complexes and play critical roles in cellular signaling, metabolic pathways, and macromolecular complex stability[3][5]. Notably, **protein-protein interfaces can be considered potential therapeutic sites** for small-molecule or biologic inhibitors aiming to disrupt pathological protein-protein interactions, but the term itself does not denote a unique, druggable protein, receptor, or enzyme[1]. Rather, it describes a *class of molecular surfaces* across many proteins. Drug discovery efforts can target specific protein-protein interfaces implicated in disease; in these cases, the canonical "target" should be the **specific protein (or complex) and its interface**, not the generic concept of a "protein-protein interface"[1]. Because this entry does **not correspond to a specific molecular entity** but to a structural region inherent in many proteins, it is considered an **incorrect or nonspecific target designation** per typical drug target databases and structured annotation requirements.