Structural and functional polymorphism of lipoprotein(a): biological and clinical implications.
Lipoprotein(a) [Lp(a)], a variant of low-density lipoprotein, is heterogeneous in density because of variability in the content and composition of its core lipids and size polymorphism of its specific glycoprotein component, apolipoprotein(a) [apo(a)]. In some individuals, density polymorphism may also derive from the fact that Lp(a) contains 2 mol of apo(a) per mole of apoB100, contrary to the more common 1:1 molar stoichiometry. Moreover, the size of apo(a) is polymorphic because of variations in the number of kringle 4 type 2 repeats. Another type of apo(a) polymorphism is related to sequence mutations at the kringle level. Two mutations can occur in kringle 4 type 10: one, Trp72-->Arg, is affiliated with an Lp(a) that is lysine-binding defective; the other, Met66-->Thr, with a normal lysine-binding function. Thus, Lp(a) is structurally and functionally polymorphic, a notion that must be considered in assessing the cardiovascular pathogenicity of this lipoprotein variant and in immunoquantification assays.
Scanu
A M
AM
Department of Medicine, University of Chicago, IL 60637.
D053299:Apolipoprotein B-100; D001054:Apolipoproteins A / Q000032:analysis / Q000235:genetics; D001055:Apolipoproteins B / Q000032:analysis; D006801:Humans; D017270:Lipoprotein(a) / Q000097:blood* / Q000737:chemistry / Q000235:genetics; D009154:Mutation; D011110:Polymorphism, Genetic; D012091:Repetitive Sequences, Nucleic Acid
D053299:Apolipoprotein B-100; D001054:Apolipoproteins A; D001055:Apolipoproteins B; D017270:Lipoprotein(a)