Involved in lipid metabolism and lipid droplet (LD) morphology, number, and size (PubMed:18093937, PubMed:18250201). Facilitates initiation of LD formation, and ensures that vectorial budding of LDs from the ER is directed towards the cytoplasm (PubMed:25540432). Concentrates at endoplasmic reticulum lipid droplet junctions. By calcium shortage. Produces supersized LDs that are up to 50 times the volume of those in wild-type cells. Present with 846 molecules/cell in log phase SD medium. Belongs to the seipin family.