Identification of the protein moiety of the LP(a)-lipoprotein in human plasma.

The structure and function of plasma lipoproteins have received increasing attention in the past few years. The recognition of the importance of the protein moiety for the structural stability and metabolism of these conjugated macromolecules has stimulated this field of research and has emphasized the careful characterization of the apo-lipoproteins for a better understanding of lipid transport and metabolism. The classification and nomenclature in the lipoprotein field have been commonly based on two sets of operational terms. Differences in the hydrated density of plasma lipoproteins, which are largely a consequence of their lipid composition and differences in their electrophoretic mobility, which is primarily a consequence of their protein moiety, have provided the basis of a widely accepted classification system, comprising four major classes, each of which is characterized by a relatively narrow density range and a distinguished electrophoretic band. These are the very low density lipoproteins (VLDL; d < 1.006 g/ml), which can be further subdivided into chylomicrons and pre$lipoproteins, the low density lipoproteins (LDL; d 1.0061.063 g/ml) with P-mobility and the high density lipoproteins (HDL; d 1.0631.2 1 glml) exhibiting a-mobility on electrophoresis. Since we know more about the protein moeity of the piasma lipoproteins, the so-called apo-lipoproteins and their distribution between the different classes, so far three distinct are characterized (apo-A, apo-B and apo-C) each of which consists of subunits,