A unique caleosin serving as the major integral protein in oil bodies isolated from Chlorella sp. cells cultured with limited nitrogen

► Oil bodies were accumulated in Chlorella sp. under a nitrogen-limited medium. ► Oil bodies in Chlorella sp. are mainly composed of triacylglycerols. ► Caleosin is present in Chlorella oil bodies as the major protein. ► Chlorella caleosin is the most primitive caleosin found in oil bodies to date.