Dictyostelium discoideum
Homologs have been identified and characterized in diverse eukaryotic organisms, including model organisms "Drosophila melanogaster" and "Caenorhabditis elegans", plants such as "Arabidopsis thaliana" and "Physcomitrella patens", and the slime mold "Dictyostelium discoideum". In these functions presenilins are thought to play a role as scaffold proteins, considered likely to be the ancestral role of the protein family.