ABSTRACT
This chapter discribes the structure of lipoprotein(a) (Lp(a)) and its apo(a) moiety are described. In vitro studies relating to the potential mechanisms of action of Lp(a) are reviewed, with emphasis on its mimicry of plasmin(ogen) function, and these studies are related to in vivo results. The structure of Lp(a) is similar to that of the low density lipoprotein particle and exhibits heterogeneity in size and density. The hydrophobic core is composed of cholesterol esters and triglycerides surrounded by a cholesterol and phospholipid monolayer. Analysis of gene structures has also established that apo(a) and plasminogen belong to the gene superfamily containing trypsin-like domains and to a branch of the family tree that consists of proteins composed of kringle and protease domains. The primary interactive functions of plasmin(ogen) are mediated by its lysine binding sites, associated with its kringle structures. Apo(a) is an intriguing molecule from the standpoint of its association with clinical pathology as well as its structure and function.
