How do membrane proteins achieve their structure and function?

Membrane proteins have unique structural features for lipid bilayer integration. Integral membrane proteins span the membrane with alpha-helical transmembrane domains (20-25 hydrophobic residues) or beta-barrel structures (in outer membranes of bacteria and mitochondria). Peripheral membrane proteins associate through electrostatic interactions or lipid anchors (GPI, myristoyl, palmitoyl). Structural determination is challenging due to lipid requirements - techniques include X-ray crystallography of detergent-solubilized proteins, cryo-EM, and computational approaches. Functions include transporters (specific solute movement), channels (gated ion flow), receptors (signal transduction), and enzymes. Membrane protein dysfunction underlies many diseases, and they comprise >50% of drug targets.