How does the hyaluronan scrap-yard operate?

Hyaluronan is an extracellular polysaccharide found throughout the extracellular matrix, especially in soft connective tissue. It has an unusual feature, in that its turnover rate is much greater than that of other extracellular matrix components. The mechanisms of its synthesis at the plasma membrane (by hyaluronan synthases) and lysosomal degradation (by hyaluronidases) are well documented. However, the mechanisms by which it enters those cells primarily involved in its degradation remain a mystery. Recent work now suggests that a novel scavenger receptor expressed on the surface of liver endothelial cells is responsible for part of this degradative process. Further study is required to fill the remaining gaps in our knowledge about this process in other tissues.