The Korean Journal of Pharmacology (대한약리학회지)
- Volume 31 Issue 2
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- Pages.241-250
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- 1995
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- 0377-9459(pISSN)
Study of an ER bound p80 Homologous to Nucleolar B23
핵소체 단백 B23과 세포질 단백 p80의 유사성에 관한 연구
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Lee, Hye-Jeong
(Department of Pharmacology, Dong-A University College of Medicine) ;
- Yoon, Sang-In (Department of Pharmacology, Dong-A University College of Medicine) ;
- Choi, Yong-Chun (Department of Pharmacology, Dong-A University College of Medicine) ;
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Ahn, Young-Soo
(Department of Pharmacology, Yonsei University College of Medicine)
- Published : 1995.09.30
Abstract
Protein B23 is one of the major nucleolar phosphoproteins associated with pre-ribosomal particles, and is localized in the granular region of the nucleolus. Recent studies suggest that protein B23 shuttles between nucleus and cytoplasm and also interacts with HIV Rev. These findings indicate that protein B23 is important in nucleocytoplasmic relationship and viral replication. However, the exact function of protein B23 is not clear yet. In acute nucleolar hypertrophy of rat liver, treated with thioacetamide, there was observed an increase of not only protein B23 but also B23-like protein p45 when anti-B23 monoclonal antibody (MAb) was used for identification. On the basis of the large B23 specific epitope structure composed of 68 amino acids, a hypothesis was formulated to examine that p45 is the pre-B23 resulting from excessive production of B23. In an attempt to investigate the precursor of B23, we analyzed the subcellular fractions and microsomal subfractions. Subsequently, we analyzed the finger printings of B23-like proteins using the tryptic peptide mapping. The results are summarized: 1) Using B23 MAb, we observed the presence of B23-like proteins in nucleolar fraction, nucleoplasmic fraction and microsomal fraction. 2) In the further microsomal subfractionation, we could partially purify B23-like protein in 2M layer of sucrose gradient. 3) When ion exchange chromatography was employed, there were protein species 80kDa(p80), 65kDa(p65) and 60kDa(p60). 4) Based on the tryptic map analysis of