Human Apolipoprotein B
Human liver apo B-100 has been cloned in plasmid and phage λgt-11 expression vectors and apo B-100 cDNA clones were identified by screening with monospecific anti-apo B antibodies and synthetic oligonucleotides based on peptides isolated and sequenced from apo B-100. Overlapping cDNA clones containing the entire apo B-100 mRNA were isolated and sequenced. All peptides previously isolated from apo B-100 mRNA were identified and their locations defined. Northern blot analysis utilizing radiolabeled cDNA probes revealed that the apoB-100 mRNA is 14.1 kb in size. On the contrary, two distinct molecular species of apo B mRNA are being produced by the small intestine. The larger-molecular-weight species migrate at the same position as liver apo B-100 mRNA. The smaller species is 7.5 kb in size, and most likely codes for apo B-48. Hybridization and nucleic acid sequence studies were carried out to define common domains and apo B-100 mRNA-specific domains. Since apo B is a single-copy gene, we propose a mechanism for the generation of apo B-100 mRNA and apo B-48 mRNA through differential splicing of the precursor apo B RNA transcript. We have also localized the apo B gene to the p23 → pter region of the short arm of chromosome 2 by filter hybridization analysis of human-mouse hybrid cell DNAs. We have also initiated studies on the gene organization and expression of apo B in patients with abetalipoproteinemia. Studies on two unrelated kindreds revealed no major deletions or insertions and that the apo B-100 mRNA and apo B-100 protein are present in the liver cells of abetalipoproteinemia patients.
KeywordsHuman Apolipoprotein Southern Blot Hybridization Analysis Partial cDNA Clone Northern Blot Hybridization Analysis Hybrid Cell Clone
Unable to display preview. Download preview PDF.
- Cardin, A. D., Witt, K. R.. Chao, J.. Margolis. H. S., Donaldson, V. H., and Jackson, R.L., 1984, Degradation of apolipoprotein B-100 of human plasma low density lipoprotein by tissue and plasma kallikreins, J. Biol. Chem. 259:8522–8528.Google Scholar
- Edge, S. B., Hoeg, J. M., Schneider, P. D., and Brewer, H. B., Jr., 1985, Adult human liver synthesizes apolipoprotein B-100, Arteriosclerosis 3:499–500.Google Scholar
- Herbert, P. N., Assmann, G., Gotto, A. M., Jr., and Fredrickson, D. S., 1983, Familial lipoprotein deficiency: Abetalipoproteinemia, hypobetalipoproteinemia, and Tangier disease, in: The Metabolic Basis of Inherited Disease (J. B. Stanbury, J. B. Wyngaarden, D. S. Fredrickson, J. L. Goldstein, and M. S. Brown, eds.), McGraw-Hill, New York, pp. 589–621.Google Scholar
- Hospattankar, A. V., Fairwell, T., Meng, M., Ronan, R., and Brewer, H. B., Jr., 1986, Identification of sequence homology between human plasma apolipoprotein B-100 and apolipoprotein B-48, J. Biol. Chem. 260:9102–9104.Google Scholar
- Kane, J. P., 1983, Apolipoprotein B: Structural and metabolic heterogeneity, Annu. Rev. Physiol. 45:637-650. Knott, T. J., Rall, S. C., Innerarity, T. L., Jacobson, S. F., Urdea, M. S., Levy-Wilson, B., Powell, L. M., Pease, R. J., Eddy, R., Nakai, H., Byers, M., Priestly, L. M., Robertson, E., Rall, L. B., Betsholtz, C., Shows, T. B., Mahley, R. W., and Scott, J., 1985, Human apolipoprotein B: Structure of carboxyl-terminal domains, sites of gene expression and chromosomal localization, Science 230:37–43.PubMedCrossRefGoogle Scholar
- Lusis, A. J., West, R., Mehrabian, M., Reuben, M. A., LeBoeuf, R. C., Kaptein, J. S., Johnson, D. F., Schumaker, V. N., Yuhasz, M. P., Schotz, M. C., and Elovson, J., 1985, Cloning and expression of apolipoprotein B, the major protein of low and very low density lipoproteins, Proc. Natl. Acad. Sci. U.S.A. 82:4596–4601.CrossRefGoogle Scholar
- Mehrabian, M., Schumaker, V. N., Fareed, G. C., West, R., Johnson, D. F., Kirchgessner, T., Lin, H. C., Wang, X., Ma, Y., Mendiaz, E., and Lusis, A. J., 1985, Human apolipoprotein B: Identification of cDNA clones and characterization of mRNA, Nucleic Acids Res. 13:6937–6953.PubMedCrossRefGoogle Scholar
- Scanu, A. M., and Teng, T., 1979, in: The Biochemistry of Atherosclerosis (A. M. Scanu, ed.), Marcel Dekker, New York, pp. 107–122.Google Scholar
- Wei, C. F., Chen, S. H., Yang, C. Y., Marcel, Y. L., Milne, R. W., Li, W. H., Sparrow, J. T., Gotto, A. M., and Chan, L., 1985, Molecular cloning and expression of partial cDNAs and deduced amino acid sequence of a carboxyl-terminal fragment of human apolipoprotein B-100, Proc. Natl. Acad. Sci. U.S.A. 82:7265–7269.PubMedCrossRefGoogle Scholar