FIGURE 1 A cell-free framework for enzyme homolog prototyping and pathway optimizing by combining cell-free protein synthesis (CFPS) with split GFP assay. (a) Biosynthetic pathways are built in a modular assembly manner. (b) Schematic representation of the strategy for the normalized screening of productive homologs. (c) Schematic representation of the workflow for building optimized biosynthetic pathway in purified enzyme systems.