Protein of unknown function DUF829. Contains exclusively eukaryote proteins including transmembrane protein 53. Said to be integral membrane proteins (!?) Dictyostelium discoideum Net4 (dicdi-q54yr8), which has strong homologies to mammalian DUF829/Tmem53/NET4 is found on lipid droplets (Du et al.). Seems to have a conserved catalytic triad Ser-113, Asp-220, and His-252 in TMEM53_HUMAN
Database
Sequences
Interpro
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IPR008547 (DUF829 Protein of unknown function DUF829, TMEM53 DUF829_TMEM53)
Across all kingdoms of life, cells store energy in a specialized organelle, the lipid droplet. In general, it consists of a hydrophobic core of triglycerides and steryl esters surrounded by only one leaflet derived from the endoplasmic reticulum membrane to which a specific set of proteins is bound. We have chosen the unicellular organism Dictyostelium discoideum to establish kinetics of lipid droplet formation and degradation and to further identify the lipid constituents and proteins of lipid droplets. Here, we show that the lipid composition is similar to what is found in mammalian lipid droplets. In addition, phospholipids preferentially consist of mainly saturated fatty acids, whereas neutral lipids are enriched in unsaturated fatty acids. Among the novel protein components are LdpA, a protein specific to Dictyostelium, and Net4, which has strong homologies to mammalian DUF829/Tmem53/NET4 that was previously only known as a constituent of the mammalian nuclear envelope. The proteins analyzed so far appear to move from the endoplasmic reticulum to the lipid droplets, supporting the concept that lipid droplets are formed on this membrane.
