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. MNSFbeta (a subunit of MNSF) is a 14.5 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 MNSFbeta in the cytosol. Recently, we have observed that Ubi-L covalently binds to intracellular proteins in mitogen-activated murine T-helper type 2 clone, D.10 cells. In this study, we purified a 33.5 kDa Ubi-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 8.5 kDa Ubi-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-G mRNA expression was increased in concanavalin A- and interferon gamma-activated D.10 cells. The 33.5 kDa Ubi-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 D.10 cells and the proliferative response of the D.10 cells. These results suggest that the post-translational modification of Bcl-G by Ubi-L might be implicated in T-cell activation.
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015151:Immunoblotting; D051379:Mice; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense; D011956:Receptors, Cell Surface; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013491:Suppressor Factors, Immunologic / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000378:metabolism
D016376:Oligonucleotides, Antisense; D011956:Receptors, Cell Surface; D013491:Suppressor Factors, Immunologic; C119949:Ubi-L receptor