Membrane proteins are proteins that are embedded within biological membranes, which separate the interior of cells from the external environment. These proteins play crucial roles in various cellular processes such as signal transduction, transport of molecules across the membrane, and cell adhesion. Membrane proteins are also important drug targets and are involved in many diseases. Studying membrane proteins is particularly challenging due to their hydrophobic nature, making them difficult to isolate and characterize. However, advances in techniques such as X-ray crystallography, cryo-electron microscopy, and protein engineering have led to significant progress in understanding the structure and function of membrane proteins.