Lipoprotein(a) as an Athero-Antifibrinolytic Risk Factor

Abstract

Lipoprotein(a) or Lp(a), discovered more than 25 years ago by Kåre Berg (2), is now known to represent a class of lipoprotein particles that have as a protein moiety apoB100 chemically complexed by a disulfide bridge to apolipoprotein(a) or apo(a), the distinctive marker of Lp(a) (12,13,18). In contrast, the plasma low density lipoproteins (LDL) have as protein moiety apoB100. Apo(a) represents a genetically quantitative trait transmitted in a Mendelian fashion (12,13,18). The two components of Lp(a) are mostly if not exclusively synthesized in the liver where the linkage between apoB100 and apo(a) takes place. The intracellular site(s) are yet to be defined and presumed to involve the unpaired cysteine residue of the 36th kringle 4-like domain of apo(a) and, probably cysteine 4190, in the carboxyl end of apoB100. The location of the disulfide attachment in apoB would account for the observation that apoB48, the apoB species made predominantly in the intestine, is not a constituent of Lp(a) (13).