(A) This heatmap summarizes the effect sizes of four mRNA attributes (avoidance of mRNA:ncRNA interaction, 5´ end secondary structure, codon bias and mRNA abundance) on protein expression as Spearman’s correlation coefficients, which are represented in gradient colors, while a starred block shows if the associated correlation is significant (p<0.05). (B) GFP expression correlates with optimized codon selection, measured by CAI (Rs = 0.29, p=0.016). (C) GFP expression correlates with 5 end secondary structure of mRNAs, measured by 5’ end intramolecular folding energy (Rs = 0.34, p=0.006). (D) GFP expression correlates with avoidance, measured by mRNA:ncRNA binding energy (Rs = 0.56, p=6.9 × 10−6). (E) Each cartoon illustrates the corresponding hypothesis; (1) optimal codon distribution (corresponding tRNAs are available for translation), (2) low 5´ end RNA structure (high folding energy of 5´ end) and (3) avoidance (fewer crosstalk interactions) lead to faster translation.