Parameters of the hypergeometric distributions used to assess the statistical significance of the IR/FOD intersections for immunoglobulin-like (Ig) fold (A) and flavodoxin (Flav) fold (B).

N represents the total number of amino acids from domains belonging to the given fold (population size), n is the total size of the given FOD class (sample size), K is the total number of MIR or LIR in the amino acid population (number of successes in the population), of which k belong to the given FOD class (number of successes in the sample, or size of the IR/FOD intersection). For a given set of parameters, the hypergeometric distribution is used to compute a p-value, i.e. the probability of observing an IR/FOD intersection of size greater than or equal to k by chance. The p-value significance threshold is set to 0.05 (for theoretical evolution of the p-value as a function of k, see Fig 6); the 95% quantile represents the size of the IR/FOD intersection which would correspond to a p-value exactly equal to 0.05, according to the given hypergeometric distribution. Parameters of the hypergeometric distributions used to assess the statistical significance of the IR/FOD intersections for immunoglobulin-like (Ig) fold (A) and flavodoxin (Flav) fold (B).