Reconstitution of Functional Integrin αIIbβ3 and Its Activation in Plasma Membrane-Mimetic Lipid Environments

The study of the platelet receptor integrin alpha IIb beta 3 in a membrane-mimetic environment without interfering signalling pathways is crucial to understand protein structure and dynamics. Our understanding of this receptor and its sequential activation steps has been tremendously progressing using structural and reconstitution approaches in model membranes, such as liposomes or supported-lipid bilayers. For most alpha IIb beta 3 reconstitution approaches, saturated short-chain lipids have been used, which is not reflecting the native platelet cell membrane composition. We report here on the reconstitution of label-free full-length alpha IIb beta 3 in liposomes containing cholesterol, sphingomyelin, and unsaturated phosphatidylcholine mimicking the plasma membrane that formed supported-lipid bilayers for quartz-crystal microbalance with dissipation (QCM-D) experiments. We demonstrate the relevance of the lipid environment and its resulting physicochemical properties on integrin reconstitution efficiency and its conformational dynamics. We present here an approach to investigate alpha IIb beta 3 in a biomimetic membrane system as a useful platform do dissect disease-relevant integrin mutations and effects on ligand binding in a lipid-specific context, which might be applicable for drug screening.

Automated summary

The importance of studying the platelet receptor integrin alpha IIb beta 3 in a membrane-mimetic environment without interfering signalling pathways lies in gaining a better understanding of protein structure and dynamics. By reconstituting the receptor in model membranes mimicking the plasma membrane, insights into integrin reconstitution efficiency and conformational dynamics can be obtained, offering a useful platform for dissecting disease-relevant integrin mutations and effects on ligand binding in a lipid-specific context, potentially applicable for drug screening.