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- Abdel-Motal, Ussama M., et al.
(författare)
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Major histocompatibility complex class I binding glycopeptides for the estimation of 'empty' class I molecules
- 1995
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Ingår i: Journal of Immunological Methods. - : Elsevier BV. - 0022-1759. ; 188:1, s. 21-31
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Tidskriftsartikel (refereegranskat)abstract
- Different forms of major histocompatibility complex (MHC) class I heavy chains are known to be expressed on the cell surface, including molecules which are functionally 'empty'. Direct peptide binding to cells is obvious during sensitization of target cells in vitro for cytotoxic T lymphocyte killing and 'empty' MHC-I molecules are comparatively abundant on TAP- 1 2 peptide transporter mutant cells. In the present work we have estimated the fraction of 'empty' MHC class I molecules using glycosylated peptides and cellular staining with carbohydrate specific monoclonal antibodies. Synthetic Db and Kb binding peptides were coupled at different positions with different di- or trisaccharides, using different spacing between the carbohydrate and the peptide backbone. Binding of sugar specific mAbs was compared in ELISA and cellular assays. An optimal Db binding glycopeptide was used for comparative staining with anti-Db and anti-carbohydrate monoclonal antibodies to estimate fractions of 'empty' molecules on different T lymphoid cells. On activated normal T cells, a large fraction of Db molecules were found to be 'empty'. The functional cole of such 'empty' MHC class I molecules on T cells is presently unclear. However, on antigen presenting cells they might participate in the antigen presentation process.
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| 2. |
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| 3. |
- Gobl, Anders E, et al.
(författare)
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Menin represses JunD-activated transcription by a histone deacetylase-dependent mechanism
- 1999
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Ingår i: Biochimica et Biophysica Acta. - 0006-3002 .- 1878-2434. ; 1447:1, s. 51-56
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Tidskriftsartikel (refereegranskat)abstract
- Recently the multiple endocrine neoplasia type 1 (MEN-1) tumor suppressor gene was cloned. MEN-1 encodes a nuclear protein, called menin, of hitherto unknown function. In order to investigate the biological function of menin we employed the yeast two-hybrid system to identify menin-interacting proteins. Here we report that menin functions as a transcriptional repressor through interaction with the transcription factor JunD. The interaction is mediated via the N-terminal transcription activation domain of JunD, and the C-terminal part of menin. In transient co-transfection experiments, expression of menin leads to specific repression of JunD transcriptional activity, which is dependent on the integrity of the menin C-terminal region. C-Terminal truncations of the protein not only abolish repression, but increase JunD transcriptional activity, implying the existence of a functional domain separate from the JunD-binding region. Menin-mediated repression is relieved by the histone deacetylase inhibitor trichostatin A, indicating that deacetylation of histones is an essential component of this repression mechanism, as has recently been demonstrated for the retinoblastoma protein. Missense, in-frame deletions, frameshift and nonsense mutations lead to inactivation of menin or possibly to truncated proteins. This would result in loss of repression of menin/JunD target genes, as well as non-target genes through indirect mechanisms, deregulation of cellular growth control and endocrine tumorigenesis.
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