[Lipid-protein-interactions of human apolipoproteins-structural aspects and models of lipoproteins (author's transl)].

The plasma lipoproteins are complex macromolecular structures which play an essential role in fat transport and in energy and membrane metabolism of higher organized organisms. Much has been learned in the last decade about the structural and functional interrelationships of the different lipoprotein classes. Their protein moieties, the so-called apolipoproteins, have been purified and characterized, the primary structure of four of them is known. Initial recombination experiments showed a considerable potential of the (unfractionated) lipoprotein protein to bind to lipids and to form particles similar to native lipoproteins. Further binding experiments performed in several laboratories with the purified A- and C-apolipoproteins and different physico-chemically well defined lipids have lead to the identification of lipid binding sites within the protein molecules and the formation of amphipathic helices upon and during lipid binding. This possible common mechanism of lipid-protein fractions forms the basis of a recently proposed model of one lipoprotein class, namely the high density lipoproteins (HDL). The significance of protein-protein-interactions in the formation and maintenance of these lipoprotein particles is still unknown. Whether disturbed lipid protein interactions lead to structural and/or functional alterations of the corresponding lipoproteins is a topic of discussion. The pertinent literature is listed in this paper and the physiological relevance of these studies and their clinical aspects will be presented.