The BSCL2 gene provides instructions for making a protein called seipin. Seipin is located in the membrane of a cell structure called the endoplasmic reticulum. The endoplasmic reticulum modifies newly produced proteins and helps transport proteins, fats, and other molecules to where they are needed.~Three different versions (isoforms) of the seipin protein can be produced from the BSCL2 gene. One isoform is found in most tissues, and the other two are specific to the brain and the nervous system outside of the brain.~Studies suggest that seipin plays a critical role in the development and function of adipocytes, which are the major component of fatty (adipose) tissue. Within the endoplasmic reticulum of adipocytes, seipin is involved in the formation of lipid droplets, which are structures that store fat molecules.