Hepatic lipase often found bound to HSPG, heparan sulfate proteoglycans (HSPG), keeping HL inactive and unable to bind to HDL (high density lipoprotein) or IDL (intermediate density lipoprotein). When it is free in the bloodstream, however, it is found associated with HDL to maintain it inactive. This is because the triacylglycerides in HDL serve as a substrate, but the lipoprotein contains proteins around the triacylglycerides that can prevent the triacylglycerides from being broken down by HL. One of the principal functions of hepatic lipase is to convert intermediate-density lipoprotein (IDL) to low-density lipoprotein (LDL). Hepatic lipase thus plays an important role in
Spermaceti organ Spermaceti organ The spermaceti organ is an organ that commonly appears in the heads of toothed whales of the family Physeteroidea, in particular the sperm whale. This organ contains a waxy liquid called spermaceti and is involved in the generation of sound. In the modern day Great Sperm Whale ("Physeter macrocephalus"), the spermaceti organ is far larger in proportion to the animal’s body than what would be explained by simple allometry, and the evolution of the organ has caused changes in basal skull morphology, which may implicate tradeoffs were made that compromised the functionality of other nearby features. The high