Fig. 8

Illustration of the principle behind Algorithm 1. An illustration of how the birth and death times of an mRNA molecule are used to obtain the number of proteins that were produced from it and then survived until the time at which mRNA and protein numbers were measured. According to the two-state model used here, the number of protein molecules that were translated using a given mRNA template and have not yet been degraded can be found by sampling from the corresponding Poisson distribution with a parameter which depends on the lifetime of the mRNA template. If the mRNA is degraded before the measurement time point, the remaining protein molecules are assumed to decay exponentially. Thus the number of protein molecules can be obtained by first sampling the number present at the point of mRNA decay and then sampling from the corresponding binomial distribution to determine the number of surviving molecules at the measurement time point