What is homology?
Homology describes the similarities in genes or protein sequences of species with a common ancestor. Thus, homologous proteins will not always share the same exact function, but must be derived from a common ancestor. Using Ensembl, Homologene, and the BLAST alignment tool, homologs of the human complement C4-A isoform 1 preproprotein were determined and later used to generate phylogenetic trees. The species, protein name, accession code (with link to FASTA page), and percent identity of homologs are shown below.