The study presents an analysis of how different cellular functions link cell size to the expression of synthetic genes in E. coli. The Size-Expression interaction was mapped with a two-gene genetic probe across 3800 single-gene deletion strains. Through regression analysis, expression-specific effects and gene-specific effects were derived from size effects and generic expression effects, respectively. The entire compendium of cell functions broadly mapped to four systems of distinct primary influence on the Size-Expression map. Specifically, membrane structural components primarily affected size, whereas protein and RNA stability primarily affected gene expression. In addition, major Size-Expression shifts showed no substantial gene-specific effects unless they were mediated by key components of the protein synthesis apparatus.