We have recently developed methods for the extraction, separation and analysis of lipids from yeast cell cultures as physiologically realistic targets for membrane binding drugs such as the antifungal agent Amphotericin B. Our previous results using NR on supported bilayers have shown that the structural consequences of Amphotericin B intricately depend on the membrane lipid composition, in particular of polyunsaturated lipids. In this joint Diamond-ISIS proposal we aim to use a combination of NR, XRR and GIXD to obtain a more detailed picture of yeast lipid structures in monolayers at the air-water interface, in particular the headgroup conformation and the degree of chain ordering, and how AmB changes these. There results will enable a better understanding of the effects of AMB in our yeast lipid membranes and those previously published on model lipid monolayers.