Figure 4.

The Effects of Initiation Probabilities on Protein Production and Pool of Free Ribosomes

(A and B) As in Figure 2, we simulated translation of a transgene added to a wild-type yeast cell. Transgene mRNA levels were set at 25% of all cellular mRNA. We measured the number of transgene proteins produced per transgene mRNA (A), as well as the equilibrium fraction of ribosomes that are free (B); both quantities are expressed relative to the case of transgene with CAI ≈ 0. The dashed vertical line denotes the average initiation probability of endogenous yeast genes. Increasing codon bias of a transgene significantly increases the rate of protein production only when the transgene’s initiation probability exceeds the average initiation probability of endogenous genes. See also Table S4 and Figure S2.