Conformation of apolipoprotein B-100 in the low density lipoproteins of tangier disease. Identification of localized conformational response to triglyceride content
| Autor: | G C Chen, Clive R. Pullinger, J W Schilling, P Hass, J Scott, Steven T. Kunitake, Saiyong Zhu, R J Pease, John P. Kane, Stephen G. Young |
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| Rok vydání: | 1990 |
| Předmět: |
Protease
medicine.diagnostic_test Apolipoprotein B biology Triglyceride medicine.drug_class medicine.medical_treatment Proteolysis Proteolytic enzymes nutritional and metabolic diseases Cell Biology medicine.disease Monoclonal antibody Biochemistry Epitope chemistry.chemical_compound Tangier disease chemistry medicine biology.protein lipids (amino acids peptides and proteins) Molecular Biology |
| Zdroj: | Journal of Biological Chemistry. 265:20739-20746 |
| ISSN: | 0021-9258 |
| DOI: | 10.1016/s0021-9258(17)45278-1 |
| Popis: | The low density lipoproteins (LDL) from patients with Tangier disease are enriched in triglycerides, 27% of LDL mass versus 7% for normal LDL. To study whether this unique LDL core lipid composition affects the surface disposition of apolipoprotein (apo) B-100, we analyzed the LDL by protease digestion and in competitive radioimmunoassays. Limited proteolytic digestion of Tangier LDL by Staphylococcus aureus V8 protease generated a prominent fragment of 120 kDa (cleavage site at residue 1076), which was not visible in similarly digested normal LDL. In competitive radioimmunoassay, Tangier LDL bound weakly to the apoB-specific monoclonal antibody MB20, compared with control LDL. We localized the MB20 epitope between residues 1031 and 1084 of apoB-100, probably very near residue 1076. DNA sequencing of exon 21 of apoB genomic clones (coding for residues 1014-1084) from a Tangier patient revealed no difference from the normal DNA sequence, thus eliminating a protein polymorphism as a basis for the altered protease sensitivity and antibody binding. When the triglyceride contents of Tangier LDL were reduced to 10% of mass by incubation with normal high density lipoproteins, production of the 120-kDa fragment by proteolysis decreased and MB20 binding increased in affinity, implying a change toward normal conformation of apoB-100. Thus, using two independent techniques, proteolytic digestion and binding of monoclonal antibodies, we have demonstrated an alternative conformation of apoB-100 in the vicinity of residue 1076, which reflects the content of triglycerides in the LDL particle. |
| Databáze: | OpenAIRE |
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