Cells maintain the specific lipid composition of distinct organelles by vesicular
transport as well as non-vesicular lipid trafficking via lipid transport proteins.
Oxysterol-binding proteins (OSBPs) are a family of lipid transport proteins that transfer
lipids at various membrane contact sites (MCSs). OSBPs have been extensively investigated
in human and yeast cells where 12 have been identified inHomo sapiensand 7 inSaccharomyces cerevisiae. The evolutionary relationship between
these well-characterized OSBPs is still unclear. By reconstructing phylogenies of
eukaryote OSBPs, we show that the ancestral Saccharomycotina had four OSBPs, the ancestral
fungus had five OSBPs, and the ancestral animal had six OSBPs, whereas the shared ancestor
of animals and fungi as well as the ancestral eukaryote had only three OSBPs. Our analyses
identified three undescribed ancient OSBP orthologues, one fungal OSBP (Osh8) lost in the
lineage leading to yeast, one animal OSBP (ORP12) lost in the lineage leading to
vertebrates, and one eukaryotic OSBP (OshEu) lost in both the animal and fungal
lineages.