In contrast to the notion established for many years that protein function depends on rigid 3D structures,nowadays there is importantevidence suggesting that non-structured segments of proteins play important roles in protein function.Therefore,disorder-to-orderdynamic conformational transitions have been proposed as an attractive mechanism involved in protein-protein recognition.Our laboratoryusing Langmuir monolayers of apolipoproteins has previously shown that upon lateral compression at the air/water andphospholipid/water interfaces,there is an important movement of the C-terminal segment of apolipoprotein CI towards the air,consideredthe hydrophobic region of the monolayer and the acyl-chain region of the interface when phospholipids are used.