Signal peptide is a conserved feature of homologous proteins.

<p>Homologous proteins of human/mouse, human/fruit fly, and human/C. elegans were extracted from HomoloGene triplets. The proportion of matching protein pairs, in which both proteins have or lack a signal peptide, was calculated for each pair of organisms (gray columns). For comparison, the expected proportions (black columns), is calculated under the assumption that signal peptide is not conserved between homologs, using the prevalence of proteins having signal peptides in each organism.