Protein complexes are groups of two or more proteins that interact with each other to perform a specific biological function. These complexes are vital for many cellular processes, such as signaling pathways, gene regulation, and metabolism. The interactions between proteins within a complex are often dynamic and can be influenced by various factors, including post-translational modifications, cellular conditions, and external stimuli. Studying protein complexes is important for understanding the underlying mechanisms of biological processes and diseases, as well as for developing therapies targeting specific protein-protein interactions. Techniques such as mass spectrometry, structural biology, and biochemical assays are commonly used to investigate protein complexes and their functions.