Separation and Identification of APO-B-Containing Lipoprotein Particles in Normolipidemic Subjects and Patients with Hyperlipoproteinemias

Abstract

The operationally-defined plasma lipoproteins have provided the theoretical basis for most studies and current views on the mechanism of lipid transport [1,2]. The popularity of these classification systems has been enhanced by clinical studies which have related certain derangements of lipid transport to particular density classes or electrophoretic patterns [2,3]. However, the discovery of a number of apolipoproteins [1,4] and the detection of marked protein heterogeneity of lipoprotein density classes and electrophoretic bands [4,5] have become incompatible with the view that operationally-defined lipoproteins represent the fundamental chemical and metabolic entities of lipid transport system. Results from laboratories have shown that major density classes consist of several distinct lipoprotein families or particles rather than single lipid-protein complexes [4-9]. Based on these and similar findings showing that lipoprotein density classes consist of distinct lipoprotein particles of similar hydrated densities but different apolipoprotein composition, we have proposed that apo-lipoproteins be used as specific markers for the identification of lipoprotein particles and as a new means for the classification of plasma lipoproteins [10,11]. According to this proposal, lipoprotein families or particles which contain a single apolipoprotein are called simple lipoproteins and those which contain two or more apolipoproteins are referred to as complex lipoproteins [11]. The nomenclature of lipoprotein particles is based on the ABC nomenclature of apolipoproteins [10] in that lipoprotein particles are named after their constitutive apolipoproteins. For example, lipoprotein particles which only contain ApoB as their protein moiety are called lipoprotein B (LP-B), while lipoprotein particles which contain apolipoproteins B, C and E are named lipoprotein B:C:E (LP-B:C:E).