Monolayers on a Langmuir trough constitute a great biomimetic model to characterize protein-protein or protein-lipid interaction, where the physical state of the interfacial layer is completely controlled. We present here three studies performed on monolayers, with a wide panel of experimental (optical, spectroscopical, rheological) techniques. i) Surface properties and conformation of Nephila clavipes Spider recombinant silk proteins (MaSpI and MaSp2) was studied at the air-water interface: we show that the mechanism of assembly of both proteins is different, although both proteins share the same sequence pattern and a close hydrophobicity. They both exhibit a certain propensity to form b-sheets that may be important for the efficiency of the natural spinning process. ii) The dystrophin molecular organization and its anchoring in a lipidic environment depend on the rod fragment used and on the lipid nature. Moreover the interaction is guided by the lateral surface pressure. This lipid packing variation is essential to understand the role of the dystrophin during compression-extension cycle of the muscle membrane. iii) We evidence that non additive behavior of mixtures of food globular proteins leads to enhanced foaming properties or to self assembled objects.