Abstract
<jats:p>Hybrid membranes (HMs) composed of amphiphilic block copolymers and lipids exhibit diverse phase behavior controlled by polymer length and weight fraction. We show that lipid-rich nanodomains form only within a narrow compositional window, limiting their role in creating native-like environments for membrane proteins. In mixed HMs, we identify a distinct mechanism whereby hydrophobic mismatch induces membrane defects that dynamically recruit lipids and displace the polymer, reducing the energetic cost of protein accommodation. This reorganization is coupled to protein conformational state and alters the local availability of individual lipid species. Using the synthetic membrane protein ROCKET, we further show that lipid enrichment can reshape preferential lipid–protein interactions while preserving established cardiolipin recognition. Local enrichment appears to promote, but is not sufficient for, preferential binding. By linking phase behavior, protein-induced membrane remodeling, and lipid recognition, our findings provide a mechanistic framework for understanding and rationally designing biomimetic HMs that support functional membrane proteins for applications in synthetic cells and membrane-based nanotechnology.</jats:p>