<prompt> Answer this question truthfullyWhat is the function of lipoprotein?  <response>: <reason> Lpa is assembled at the hepatocyte cell membrane surface, while other scenarios exist with regard to the location of assembly. It mainly exists in plasma. Lpa contributes to the process of atherogenesis. Because of its structural similarity to plasminogen and tissue plasminogen activator, competitive inhibition leads to reduced fibrinolysis, and as a result of the stimulation of secretion of plasminogen activator inhibitor 1, Lpa leads to thrombogenesis. It also may enhance coagulation by inhibiting the function of tissue factor pathway inhibitor. Lpa carries cholesterol and binds atherogenic proinflammatory oxidized phospholipids as a preferential carrier of oxidized phospholipids in human plasma, which attract inflammatory cells to vessel walls and leads to smooth muscle cell proliferation. Moreover, Lpa also is hypothesized to be involved in wound healing and tissue repair, interacting with components of the vascular wall and extra cellular matrix. Apoa, a distinct feature of the Lpa particle, binds to immobilized fibronectin and endows Lpa with the serine-proteinase-type proteolytic activity. Nonetheless, individuals without Lpa or with very low Lpa levels seem to be healthy. Thus, plasma Lpa is not vital, at least under normal environmental conditions. Since apoaLpa derived rather recently in mammalian evolution - only old world monkeys and humans have been shown to harbour Lpa - its function might not be vital, but just evolutionarily advantageous under certain environmental conditions, e.g. in case of exposure to certain infectious diseases.Another possibility, suggested by Linus Pauling, is that Lpa is a primate adaptation to L-gulonolactone oxidase GULO deficiency, found only in certain lines of mammals. GULO is required for converting glucose to ascorbic acid vitamin C, which is needed to repair arteries; following the loss of GULO, those primates who adopted diets less abundant in vitamin C may have used Lpa as an ascorbic-acid surrogate to repair arterial walls. 