Fig. 12.

Schematic diagram depicting the impact of sortilin on Lp(a) metabolism. Apo(a) encounters an apoB-containing particle within the hepatocyte, perhaps in the ER; the nature of this particle is unknown and hence is depicted with a question mark. Sortilin is able to direct apoB-containing particles like VLDL to presecretory degradation, but it has the opposite effect on nascent Lp(a), for reasons that remain unclear. Lp(a) can be cleared by several different hepatic receptors; clearance of Lp(a) through sortilin is likely mediated by another apoB-containing particle to which Lp(a) can bind. apo(a), apolipoprotein(a); Lp(a), lipoprotein(a); ER, endoplasmic reticulum