Tangier disease: a structural defect in apolipoprotein A-I (apoA-I Tangier).
AUTOR(ES)
Kay, L L
RESUMO
Tangier disease is a familial disorder characterized by orange tonsils, cholesterol ester deposition in reticuloendothelial cells, abnormal chylomicron remnants, and a marked reduction in high density lipoproteins. Plasma concentrations of the apolipoproteins apo-A-I and apoA-II in patients with Tangier disease are approximately 1% and 7% of those in normal subjects, respectively. Previous studies have shown that the low plasma concentrations of apoA-I and apoA-II are due to increased fractional catabolism with a relatively normal apoA-I and apoA-II synthesis. Plasma apoA-I and apoA-II were isolated to electrophoretic homogeneity from delipidated plasma lipoproteins from a patient with Tangier disease. ApoA-I Tangier differed from apoA-I from control subjects in amino acid composition, electrophoretic mobility, apparent molecular weight on sodium dodecyl sulfate/polyacrylamide gel electrophoresis, and heterogeneity of isoforms on isoelectric focusing. ApoA-II Tangier, however, appeared to be identical to normal apoA-II in amino acid composition and in immunological as well as chemical properties. These results have been interpreted as indicating that apoA-I Tangier has a different covalent structure than does normal apoA-I, and apoA-II Tangier is identical to normal apoA-II. This structural change in apoA-I Tangier is associated with rapid catabolism of apoA-I Tangier-and apoA-II Tangier-containing plasma lipoproteins, and it leads to the deficiency in high density lipoproteins, abnormal chylomicron remnants, and the intracellular accumulation of cholesterol ester characteristic of Tangier disease.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=346223Documentos Relacionados
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