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Seipin and similar proteins Seipin is a homo-oligomeric integral membrane protein in the endoplasmic reticulum (ER) that concentrates at junctions with cytoplasmic lipid droplets (LDs). It acts as a cell-autonomous regulator of lipolysis essential for adipocyte differentiation. Seipin is predicted to contain two transmembrane domains at N-terminus and C-terminus, respectively. Human seipin, also called Bernardinelli-Seip congenital lipodystrophy type 2 protein (BSCL2), may contain a third transmembrane domain in the middle region. Mutations in the seipin gene underlie human congenital generalized lipodystrophy. Seipin may also be implicated in Silver spastic paraplegia syndrome and distal hereditary motor neuropathy type V. Seipin homologs from fungi, plants, and insects are also included in this family. There are three SEIPIN homologs in Arabidopsis thaliana, designated SEIPIN1, SEIPIN2, and SEIPIN3. Saccharomyces cerevisiae Seipin (Sei1) is also called few lipid droplets protein 1 (Fld1p). Similar to their animal homologs, plant and yeast seipins also play roles in lipid droplet (LD) biogenesis. Human seipin exists as an undecamer, and this oligomerization state is critical for its physiological function. In contrast to Human seipin, S. cerevisiae Sei1-mediated LD formation depends on Ldb16, a yeast specific binding partner. Sei1 forms a homodecameric ring that scaffolds and positions Ldb16. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",