Protein assembly refers to the process by which multiple protein subunits come together to form a larger, functional protein complex. This complex can have specific structural or functional roles in biological processes such as cellular signaling, DNA replication, and immune response. Protein assembly can be driven by various interactions between the subunits, including non-covalent interactions such as hydrogen bonding, hydrophobic interactions, and electrostatic interactions. Understanding protein assembly is essential for elucidating the mechanisms by which proteins carry out their biological functions and for developing new therapeutics targeting protein complexes. Techniques such as X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and cryo-electron microscopy are commonly used to study protein assembly.