17beta-Hydroxysteroid dehydrogenase type 13 is a liver-specific lipid droplet-associated protein.

17beta-Hydroxysteroid dehydrogenase (17betaHSD) type 13 is identified as a new lipid droplet-associated protein. 17betaHSD type 13 has an N-terminal sequence similar to that of 17betaHSD type 11, and both sequences function as an endoplasmic reticulum and lipid droplet-targeting signal. Localization of native 17betaHSD type 13 on the lipid droplets was confirmed by subcellular fractionation and Western blotting. In contrast to 17betaHSD type 11, however, expression of 17betaHSD type 13 is largely restricted to the liver and is not enhanced by peroxisome proliferator-activated receptor alpha and its ligand. Instead the expression level of 17betaHSD type 13 in the receptor-null mice was increased several-fold. 17betaHSD type 13 may have a distinct physiological role as a lipid droplet-associated protein in the liver.