tailieunhanh - Báo cáo khoa học: Characterization of ubiquitin-like polypeptide acceptor protein, a novel pro-apoptotic member of the Bcl2 family

Monoclonal nonspecific suppressor factor (MNSF) is a cytokine with antigen nonspecific suppressive activity. MNSFb(a subunit of MNSF) is a fusion protein consisting of a proteinwith 36%identitywith ubiquitin and ribosomal protein S30. The ubiquitin-like segment (Ubi-L) may be cleaved from MNSFbin the cytosol. Recently, we have observed that Ubi-L covalently binds to intracellular proteins in mitogen-activated murine T-helper type 2 clone, cells. | Eur. J. Biochem. 270 4052-4058 2003 FEBS 2003 doi Characterization of ubiquitin-like polypeptide acceptor protein a novel pro-apoptotic member of the Bcl2 family Morihiko Nakamura1 and Yoshinori Tanigawa2 1 Cooperative Medical Research Center and 2Department of Biochemistry Shimane Medical University Japan Monoclonal nonspecific suppressor factor MNSF is a cytokine with antigen nonspecific suppressive activity. MNSFb a subunit of MNSF is a kDa fusion protein consisting of a protein with 36 identity with ubiquitin and ribosomal protein S30. The ubiquitin-like segment Ubi-L may be cleaved from MNSFb in the cytosol. Recently we have observed that Ubi-L covalently binds to intracellular proteins in mitogen-activated murine T-helper type 2 clone cells. In this study we purified a kDa Ehí-L adduct from D. 10 cell lysates by sequential chromatography on DEAE anti- Ubi-L Ig-conjugated Sepharose and hydroxylapatite. MALDI-TOF-MS fingerprinting revealed that this Ubi-L adduct consists of an kDa Ehí-L and a Bcl2-like protein murine orthologue of a previously cloned human BCL-G gene product with pro-apoptotic function. Murine Bcl-G mRNA was highly expressed in testis and significantly in spleen. In addition the level of Bcl-GmRNA expression was increased in concanavalin A- and interferon y-activated cells. The kDa Ubí-L adduct was expressed in spleen but not in testis even though Bcl-G protein was highly expressed in this tissue. The antisense oligonucleotide to Bcl-G significantly decreased the level of the Ubi-L adduct formation in concanavalin A-activated cells and the proliferative response of the cells. These results suggest that the post-translational modification of Bcl-G by Ubi-L might be implicated in T-cell activation. Keywords Bcl2 T-cell ubiquitin-like protein. The covalent attachment of ubiquitin to proteins and their subsequent degradation by the 26 S proteasome represents the most commonly .